Mystery Crank

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).

Overview

The Mystery Crank is the first game mode that was first introduced to every player. For each pulls, the player will be awarded with unit (unit parts) or items depending on their pull's outcome.

Crank Keys

Initially introduced for the defunct titular Extra Ops at the update 1.8.0, the Crank Keys can be obtained in many ways. It allow free pulls within the Mystery Crank, while collecting 10 pieces of it provides 10 plays.

Icon	Name	Notes
	MSP Crank Key	Used for MSP Cranks. It never expires and can be used indefinitely.
	Medal Crank Key	Used for Medal Cranks. It will be used automatically after the current pick up the crank contains has expired.
	VIP Crank Key	Defunct, used for VIP Crank. It will be used automatically after a week later.
	TF Crank Key	Used for Task Force Extra Ops. It will be used automatically after the event ends.

Medal Crank Keys can be obtained through the following:

• Step Up Crank's 2nd and 5th step.
• Extra Ops

MSP Crank keys are obtained by tapping on the Fat Fio that appears in the main screen.

The Genie

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. Icons of a greater amount than that required for an unlock do not trigger the genie animation, even though they're obviously more valuable.

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 featured part icons, a normal Genie will appear. If the player rolls a 30x icon on a normal Box Crank, or an 80x icon on a Campaign Box Crank, the Genie tries to appear normally - only to retreat back to the crank and reappear as a golden Genie.

On exceedingly rare occasions, the crank sequence will be interrupted by the appearance of Eri and Nadia, riding a Regular Army Helicopter. Before the crank icons are revealed they'll destroy them, leading to a fresh set which includes the featured prize. If the old set did not have a genie, then the new set will contain either a normal or golden genie. If the old set did have a normal genie, then the new set will contain 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.

In Fever Cranks, both normal and golden Genies can appear in the crank. Contrary to the other two cranks, normal genies here are seen more of a hinderance than boon as they always indicate the presence of a 5/10x of the featured unit or a random 30x Super Rare unit. Golden Genies appear whenever the player pulls the 80x of the featured unit.

List of Cranks

MSP and Medal Cranks are always available to be accessed at any time. All other cranks are limited time only.

Step, box and fever cranks usually alternate between each other, which usually indicates which the next crank would usually be. Fever cranks are rarer than boxes, although they still follow the same rule as stated before. Occasionally the crank order may be disrupted for consecutive cranks of the same type, which is usually the case during updates.

An example of a typical rotation would be Step > Fever/Box > Step. The more uncommon rotation would be Step > Step > Fever/Box.

Lucky Bag, premium and reproduction cranks are side-on additions and thus do not have any impact on the crank rotation.

MSP Crank

By consuming MSP unit any items are to come.

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 whenever she appears on the game's menu screen.

Prize	30x	10x	3x	10x	3x	3x	8x
Odds	0.182%	0.91%	2.73%	7.8%	23.4%	23.4%	41.6%

* Odds are approximations, and may be subject to frequent change.

Medal Crank

★ Complete ≪10 PLAY≫ to be sure to get Units.

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 would always 80x parts for at least one Super Rare Unit (allowing a silver unlock). Following the removal of all Super Rare units from the Medal Crank, 30x parts for a Rare are provided instead (allowing a bronze unlock).

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, in varying amounts according to the event type (eg three from Marathon / Rare Boss events, ten or more from most others). They're also provided on the second and fifth steps of the Step Up Crank. Such keys expire at the end of the featured unit's pickup, and any keys that remain when the current pickup is over will be used automatically. In this case, the rewards are placed in the player's mailbox.

As of the 3.0.0 update, the VIP Crank's perks were moved to the Medal Crank. Players who have a VIP level of 11 or higher now draw an additional regular platinum item of their choice when performing 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 each day.

The content of the Medal Crank frequently changes. The most recent additions are marked as "pickup units", offering boosted appearance rates, and bonus points when used in Extra Ops events. With each new unit placed in the Medal Crank's prize list, the oldest ones are removed and generally placed into various Shops requiring free currencies. The pickup units from the Extra Ops in the update they were made such are generally put in the Rare/Extra Shop in the next update.

Although the pre-acquisition unit states that they will appear roughly 30 days following their initial release, this is false due to the pickup sequence having been interrupted by special Status Strengthening pickups, which replace what would have been the next pickup unit with three older units serving as the pickup, awarding 110 parts instead of 30, along with individual Status Strengthening items in the pool.

During Dream Lotteries, each paid pull from the Medal Crank yields a single ticket.

Prize	80x	30x	10x	30x	10x	1x	1x
Odds	1.32%	6.57%	18.405%	12.097%	34%	4.818%	22.789%

* Odds are approximations, and may be subject to frequent change.

Box Crank

Main article: Mystery Crank/Box

Currently two Box Cranks are in circulation - the Campaign Box Crank and TF Box Crank, the latter of which is Extra Ops-exclusive. Campaign Box Cranks alternate with Step Up Cranks, outside of reproductions.

Step Up Crank

Main article: Mystery Crank/Step

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. Step Up Cranks alternate with Campaign Box Cranks, outside of reproductions.

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 first, third and fourth spin also gives a MSP reward, while the second and fifth provide a Medal Crank key.

Fever Crank

Main article: Mystery Crank/Fever

A Mystery Crank first introduced in 6.0.0. It features a similar pool of items with the Box Crank in addition to a new "Fever" system.

Lucky Bag Crank

Main article: Mystery Crank/Lucky Bag

Premium Crank

Main article: Mystery Crank/Premium

Supporter Crank

Main article: Mystery Crank/Supporter

Defunct Cranks

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VIP Crank

★ Perform "10 PLAYS" to be sure to get at least respectively more than one SR Unit and Platinum item.

This crank was unlocked upon reaching VIP level 11 (20,000 VIP EXP) and offered a free spin every 24 hours ^{[as of 1.3.0]} after reaching VIP 14 (80,000 VIP EXP). It was very similar to the regular Medal Crank, with the same cost-per-play and prize list: however, its odds were re-weighted and a 10x spin guaranteed a regular platinum item in addition to the usual 80-part Super Rare icon. Despite the forced inclusion of an item icon, it still averaged a slightly higher Super Rare part output than the regular Medal Crank.

Gold Crank keys could be obtained which allowed free spins of the VIP crank. These were awarded through Crank Key Extra Ops, as well as every fifth spin of a Step Up Crank.

The VIP Crank was removed as of the update of 3.0.0. Players at VIP 11 now gain an additional platinum equip item of their choice when spinning the regular Medal Crank.

Prize	80x	30x	10x	30x	10x	1x	1x
Odds	1.32%	7.89%	26.295%	8.947%	27.7%	9.636%	18.226%

* Odds are approximations, and may be subject to frequent change.

Event Crank

★ Play 10 times in order to get at least 30 parts of 2 SR Units.

First appearing in 1.3.0, and last in 3.7.0(?), this crank dropped 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 were available - even those available in the MSP Crank. Performing a 10x spin guaranteed the appearance of at least two 30-part Super Rare icons.

The Event Crank was only available during limited time periods, and typically had a new prize list every time it surfaced (based upon a theme, often involving units that weren't available elsewhere). The two 30-part Super Rare Icons were fairly unique; one of these would be selected from a pool including every Super Rare unit. The second icon came from a pool containing only the crank's "featured" units.

The Event Crank was recommended as a cost-efficient method of obtaining a desired Super Rare unit. At the worst case, 5,400 medals were required in order to obtain a featured unit, as long as it was a single-feature unit. Usually, single-feature Event Cranks occurred roughly one month after the featured unit had been placed on the Mystery Crank.

Prize	30x	10x	30x	10x	10x	5x
Odds	3.564%	15.59%	4.014%	40.086%	3.34%	33.41%

* Odds are approximations, and may be subject to frequent change.