The Mystery Cranks are a gacha-based system in Metal Slug Attack, offering random Units and Items in exchange for either Medals or MSP. Many of the more powerful units are only available via the medal-based cranks.
Each day, a daily quest gives the player 80 XP and 5,000 MSP when any crank is pulled (resetting at 4am JST).
As the name implies, this crank takes in payments of MSP: 10,000 for a single spin, or 90,000 for ten spins at a time (10% cheaper than 10 individual spins). This Crank is often used to gain obtain and bronze items for all levels.
It offers scheduled free single spins at regular intervals throughout the day (JST):
- 0700 - 0900 hours.
- 1200 - 1400 hours.
- 1500 - 1700 hours.
- 1800 - 2000 hours.
- 2200 - 0000 hours.
Bronze crank keys (allowing free spins) can also be obtained by tapping Fat Fio when she appears on the game's menu screen.
As the name implies, this crank takes in payments of Medals: 300 for a single spin, or 2,600 for ten spins at a time (13.33% cheaper than 10 individual pulls). As of 1.4.0, a 10x spin will always grant a single Super Rare Unit. As of 3.0.0, the Crank now gives a single Rare or Super Rare unit.
One free spin can be performed each day (resetting at 4am JST[as of 1.17.0]). Silver crank keys can occasionally be obtained during Extra Ops - either from the challenges themselves (offering 3 for Single Map and Rare Boss-type Ops, and up to 12 during Daily Rank-type ops). These keys can also be obtained from the second and fifth steps in the Step Up Crank (see below). These keys expire at the end of the featured unit's pickup, and any keys that remain when the current pickup is over will be converted into random rewards from the Mystery Crank.
As of the 3.0.0 update, the VIP Crank's perks were moved into the Medal Crank. Players who have a VIP level of 11 and higher will now draw a random platinum item (which can be picked) whenever doing a 10x play on the Medal Crank. Players with a VIP level of 14 or higher are given a second free chance on the Medal Crank.
The content of the Medal Crank frequently changes. The most recent additions are marked as "pickup units", have boosted appearance rates, and offer bonus points if used in Extra Ops events. The oldest units are eventually removed (Mostly rare units), most commonly re-appearing in the Shops.
This crank is unlocked upon reaching VIP level 11 (20,000 VIP EXP) and offers a free spin every 24 hours [as of 1.3.0] after reaching VIP 14 (80,000 VIP EXP). It's very similar to the regular Medal Crank, with the same cost-per-play and prize list: however, its odds are re-weighted and a 10x spin guarantees a platinum item in addition to the usual 80-part Super Rare icon. Despite this, it still averages a slightly higher Super Rare part output.
Gold Crank keys are significantly rarer, currently only being available during Step Up cranks, when the player reaches the fifth step.
The VIP Crank was removed as of the update of 3.0.0. Perks of the VIP Crank were moved into the Medal Crank.
First appearing in 1.3.0, this crank drops units exclusively and at a cheaper price than the Medal Crank: 200 medals for a single spin, or 1,800 for ten spins at a time (10% cost discounted). Units of *all* rarities are available - even those available in the MSP Crank. Performing a 10x spin guarantees the appearance of at least two 30-part Super Rare icons.
The Event Crank is only available during limited time periods, and typically has a new prize list every time it surfaces (based upon a theme, often involving units that aren't available elsewhere). The two 30-part Super Rare Icons are fairly unique; one of these will include every Super Rare unit. The second one is similar to the first one previously mentioned, except that it will only contain the featured Super Rare unit(s).
The Event Crank is recommended at a cost-efficient method of obtaining a desired Super Rare unit. At the worst case, 5,400 medals are required in order to obtain the featured unit, as long as it is a single-feature unit. Usually, single-feature Event Cranks occur roughly one month after the featured unit has been placed on the Mystery Crank.
Standard Box Crank
Introduced in 2.0.0, the Box Crank is a new crank added to the game. Like the Event Crank, it's only available during limited-time events, with a different prize list upon each appearance. Plays are performed solely as 10x spins for 800 medals, although the first pull is free. The Box Crank only contains unit parts (any rarity), although the first also contained platinum and gold items.
Uniquely, all prize icons have equal odds, and are removed from the 250-icon prize pool as they appear, meaning that twenty-five 10x pulls will obtain the full set. Players can reset at any time, reverting the box back to its original state. It's also automatically reset when the box has been completely emptied. Resetting is only recommended when the best rewards are taken from the box.
Each Box Crank typically features a new "exclusive" unit which cannot be obtained via any other method. The prize pool contains five icons offering a combined 60 parts for this unit - one 30x, two 10x, and two 5x. As 80 parts are required to unlock, this means that the box has to be reset at least once in order to collect a sufficient quantity.
Some units have come with a clause noting that they will not appear on the "next" Box Crank - these "limited edition" units won't appear unless they have a reproduction, which is usually several months after they first appeared.
Only the first five Box Crank units have made repeat appearances. These units, if not being featured in a "reproduction" crank, are still extremely hard to get, with only 15 parts being offered per box.
Assuming the box is reset every time the featured unit's 30x icon appears, an average of about 20,000 medals is required to unlock it (with a standard deviation of about 5,000 medals). A slightly more efficient approach (lowering the average by several hundred medals) is to reset every time the total parts removed from the pool exceeds the number of icons removed, times 6 and divided by 25. It's recommended not to try for a featured Box Crank unit unless you're prepared to spend at least 30,000 medals in the process (with a 1/30 chance of requiring more).
Limited edition Box units are very strong, and their presence can easily turn the tide of a battle because of the various boons. Each of these "limited" units also have unique items of their own (see here for more).
For every 100 spins (or 8,000 medals spent; 7,200 for the first 100 as the first pull is free), a special avatar is rewarded to the player, meaning that icons cost 7,200, 15,200, 23,200, 31,200 and 39,200 medals respectively. Limited-edition Box Cranks have a special emerald icon which requires 770 spins, costing 60,800 medals.
Note: The "safety" feature is that when a player spends a set amount of medals, they are guaranteed the featured unit. Assuming the worst case scenario where the box crank unit parts do not appear until the end of each box, it can take up to 40,000 medals to unlock a box crank unit. This is, of course, assuming they take the least efficient option of spinning through every list until every featured part icon has been obtained before resetting - a cost of >40k is technically possible if resetting before then, though the overall most likely cost becomes much, much lower.
Reproduction Box Crank
There are two different types of reproduction Box Cranks - single and multiple feature.
The single feature is essentially the same as the original Box Crank, one featured Box (which is an old, limited box unit). However, you don't get rewards that you would normally get for obtaining parts of the unit.
The multiple feature box crank functions differently - rather than hosting one unit at a time, the oldest three box crank units are placed together in a single crank. No units of the "Normal" rarity are in this type of box, and they may carry either 180 or 250 slots.
180 slots were used during 2018's first three Box Cranks, while 250 slots were used later in the month. In 180 slot Box Cranks, icons were awarded based on the box unit in the middle. In 250 slot Box Cranks, icons vary with players obtaining the box unit's avatar icon at 300, 400 and 500 pulls respectively, though there have been a few exceptions.
Campaign Box Crank
First introduced in 3.8.0, the Campaign Box Crank functions differently compared to the standard and reproduction boxes.
No units of the "Normal" rarity are in this type of box, and this type of box crank offers old limited box units (the all-times still make an appearance here); like the all-times in the normal box crank, obtaining these parts does not trigger the Genie's appearance. Along with the all-time units, several previously limited box units make an appearance, although with less parts than what a reproduction would generally offer.
The primary box unit has a changed feature - rather than a 30x part reward, it is replaced with an 80x. This means that a player could potentially get the box unit for free and potentially cheaper to a gold/platinum frame compared to a conventional Box Crank. Despite the increased pull cost from 800 to 1,500 medals, the Campaign Box offers significantly better odds compared to a standard Box Crank, due to the presence of the 80x reward.
While pulling, there is a rare chance that a Regular Army Helicopter will appear after first pull. The presence of the helicopter means that the crank is rerolled, which will always guarantee a genie to appear.
Unlike normal box cranks, Campaign Box cranks unlock icons at different amounts; 200, 300 and 500 pulls, costing 28,500, 43,500 and 73,500 medals respectively. In addition, players automatically unlock the pre-acquisition frame of the featured unit upon obtaining 80 parts (which unlocks the unit).
List of All-Time Box Units
|White Baby (Prototype)||2.0.0||Independent|
|Rumi Aikawa||2.3.0||Regular Army|
List of Limited Box Units
|Gemini White & Black||3.5.0||Aliens|
List of Campaign Box Units
|Abigail (Subjugation Tactics)||3.16.0||Rebel Army|
Step Up Crank
The Step Up Crank was first seen in version 2.14.0, during the "Blood Runaway" event. Like the Event and Box Cranks, it is only available for limited periods of time, and only offers unit parts (either Rare or Super Rare).
Each successive pull of the crank costs more than the last, but also reveals an additional icon, making it better value for Medals. For example, the second spin reveals two icons for 560 medals (280 each), whereas the fifth spin reveals five icons for 1,100 medals (220 each). Performing five spins (at a total cost of 3,700 medals) reveals 15 icons in all (~247 medals per icon): after this, the crank automatically resets back to the first step.
The featured unit of the Step Up Crank often fills up a niche role and is powerful, though they aren't usually as strong as "limited" box units.
The Step Up can be a boon for particularly lucky players, as its possible to get platinum at a cost much lower than the box crank - however, such instances are extremely rare, and it's possible to spend more medals than the Box Crank and not obtain the unit.
Completing a set of five spins does not change the price of successive sets. Each spin grants an additional award along with its icons (either MSP or a crank key), and these rewards can also be collected multiple times by performing multiple spin sets.
|Cost per Icon||300||280||260||240||220|
Parts for the featured unit are acquired 110 at a time, with an appearance rate of 1/50 (an average cost of 12,333 medals). These are significantly better odds than those offered by the Box Crank (where the average is 20,000 for 80 parts). However, there is no "safety" feature, so players should pull at their own risk.
Note: The "safety" feature is that when a player spends a set amount of medals, they are guaranteed the featured unit. The Genie will appear if a 110x is rolled; however, it will still appear as a normal genie, so any genie that appears while pulling the crank should be taken with caution.
Once the player obtains at least one 110x reward (which basically unlocks the unit), the player automatically unlocks a special avatar.
Originally the Step Up contained a varied amount of Super Rare and Rare units. This was eventually changed, and Step Ups now offer unit parts of previous step up units in quantities of 10 and 30 parts. Unlocking the Step Up unit this way will not unlock their pre-acquisition icon, however.
Reproduction Step Up Crank
There are two different types of reproduction Step Up Cranks; single and triple reproductions.
Single reproductions give the same reward pool as what the featured unit had when they were released.
Triple reproductions feature a different reward pool, and are typically themed based on faction. The Genie will appear for any 110x pulled, though the middle unit will have a purple aura surrounding it as with a normal Step Up Crank. These reproductions are generally better than single reproductions as there is an increased chance to obtain a Step Up unit, though it still shares the same risks as the normal Step Up.
* Odds are approximations, and may be subject to frequent change.
List of Step Up Units
|Orochi Leona||2.14.0||Regular Army|
|Anastasia IV||2.17.0||Ptolemaic Army|
|Dragunov Ver.Rebellion||3.5.0||Ptolemaic Army|
|M.D.P.S-Mz 3||3.9.0||Regular Army|
|Runaway White Baby||3.15.0||Independent|
When spinning any crank, a Genie will appear before your icons are revealed. Although he doesn't grant any additional prizes, his presence does give some indication as to the value of the prizes you're about to receive.
To trigger the Genie, at least one icon won must grant the exact amount of parts required to unlock a corresponding unit. For example, an 80x Cleopatra icon will summon the Genie; whereas with a unit such as Christmas Fio or the Deformed Slug Gunner, a 10x icon is required instead (as in, as opposed to an 80x icon).
In the Box Crank, the Genie appears only when the player rolls for the featured box unit(s). If the player rolls any 5x or 10x parts, a normal Genie will appear. If the player rolls a 30x on normal Box Cranks or 80x in Campaign Box Cranks, the Genie tries to appear normally, only to retreat back to the crank and reappear as a golden Genie.
In the Step Up Crank, the Genie appears much like it normally would in the Medal Crank, except the 110x icon reward can also trigger its appearance despite not giving the exact amount of parts.
|Metal Slug Attack|
|Game Modes||Another Story | Attack! • List of Standard Missions • List of Elite Missions | Battle and Team Battle | Combat School | Extra Ops • List of Extra Ops | Online | P.O.W. Rescue | Rank Match | Special Ops|
|Features||Level and EXP | VIP | Build Up | Units • by Icon • Teams • Unobtainable | Stats | Items | Guild • List of Guild Raid Stages | Daily Login | Daily Quests | Events | Power-Up | Quests | Mystery Crank | Treasure Hunt | Shops|