Team composition and Looping

' Disclaimer: The opinions expressed in the following section are not an unequivocal only course of action, merely a single player's idea on what are good practices for various situations. '

Elements
In Million Chain, skills and leader skills are fairly pigeonholed to the color of the unit. Although some leader skills apply to multiple colors, actives are only charged by chaining the appropriate color of tile. Additionally, once you establish a loop, having additional colors becomes either extraneous or even detrimental. Therefore, it is highly recommended to run a mono color team.

Leader Skills
Leader skills are a passive effect applied to your team, based upon which unit you place in your first, leader slot in your team.

These effects can range from HP multipliers, ATK multipliers, skill charging, and so on. Aside from the leader skill from your own leader unit, you can gain an additional leader skill effect by running with an assist that is on your friends list.

If your selected assist is on your friends list, you will have both the effects of your leader skill, and their leader skill. Random assists do not give you their leader skill.

Note: Leader skills, and all skills in general, stack multiplicatively. This means if you have two leader skills, both being ATK x3 for a color, the net result is ATK x9, NOT ATK x6, as well as making ATK & guard buff actives exponentially more powerful. This can be very powerful, especially with high multipliers.

Active Skills & Why Run Mono
As mentioned previously, active skills in Million Chain are only charged by forming chains with the same color as the unit whose skill is being charged. This means that if you have a team with many colors, their skills are going to be collectively charged slower than if you were to have a mono team. This becomes especially noticeable with the meta of looping being so prominent, touched upon next.

Looping - Intro
Million Chain's meta revolves around consistently changing the panels of the board to be your particular element, allowing for enormous chains and high damage. As such, it of course becomes desirable to be able to convert the entire board to a single color every turn. To do that, "looping" is used. Looping is the act of using a pair of  matching dual panel changers to change the entire board to a color, then use that board to recharge their own skills, allowing you to convert the board every turn without pause. This in turn charges your other units' skills, allowing for tactics such as stacking buffs.

Looping II - Why Dual?
As mentioned, looping is specifically for dual changers, with some very rare exceptions. This returns to the issue of active cost, and how active skills are charged. To loop, you need to have a sufficiently low active cost that even with potentially poor board composition (low amount of 5 tiles, rainbow tiles, etc) you have a guaranteed full charge for your own skills.

The only skills capable of doing this are single, dual, and very specific triple panel conversion skills. If your skill cost is too high, you may have to spend one or more turns between converting the board, which can both prove dangerous, and gimp your damage. Below is a table of skill costs for conversion skills.

Looping III - Skill Cost Table
Key: 1C = 1 color, 2C = Two colors, 3C = 3 colors, AC = all colors, OC = own color, H = heart.

Looping IV - The Board and You
On the board, there are 33 panels. However, the RNG dictating what panels appear is not completely random, and will equalize the amount of 5 panels and rainbow panels. Total values that appear often are 36, 37, 40, and 41. Higher values are possible, but less common.

As such, to properly loop, the breakpoint is not 33 panels, but instead 36. At this point, barring enemies draining your skill gauge, you will be able to recharge your skills using any normal board composition.

Looping V - Which Units?
At this point, you may be wondering "Which panel changers do I want, then?" Ultimately, your end goal is to get a matching pair of dual panel changers. An example to this would be a pair of changers with skills Heart + Green -> Blue, and Orange + Purple -> Blue. By using a matching pair such as this, you are able to convert every non-rainbow tile on the board to your own color.

A sorted list of matching panel changers is available on the Japanese wiki. This is a great resource to bookmark!

http://wikiwiki.jp/millionchain/?2%BF%A7%CA%D1%B4%B9%A5%EB%A1%BC%A5%D7%C1%E1%B8%AB%C9%BD

Addendum - Other Useful Actives
In addition to your main panel changing skills you'll have two of your own units free for whatever skills you see fit. Listed are some of the skill types that may be useful to use.

Attack buffs: Take the form of +n% ATK for a turns. Typically, you'll want something that lasts for multiple turns, as effects stack. However, this is not binding, and higher multipliers for a lower turn count will be more desirable in certain cases.

Guard buffs: Take the form of +n% damage resist to a color or colors for a turns or a "times." For guard buffs that protect a certain number of times, it will consider one time to be one round of enemy attacks. For example, if you were hit by 3 enemies in one turn, it would consume one time. However, if you were hit 3 times over 3 turns, it would consume 3 times. For guard buffs that protect for an amount of turns, it acts in the same was as attack buffs.

Note: Guard buffs do stack. For instance, if you have two 50% guard buffs up, you will take 25% damage, and so on.

Shield breakers: Take the form of deal n damage and break one or more type(s) of shield. Fairly straightforward, these skills deal a fixed amount of damage and break enemy shields. Note that it will only break normal shields, eg. not the rainbow-colored shields that reduce damage to 0.

Enemy turn delayers: Take the form of delay enemy action by n turns. These skills add the amount on to all of the enemies' timers. For example, if there were two enemies, one with 1 turn remaining, the other with 3, delaying 8 turns would set their timers to 9 and 11, respectively. You must wait for the enemy to attack at least once before reapplying this debuff. Attempting to cast it after having already done so before the enemy has attacked you once will have no effect.

Heal over time: Take the form of heal n% HP for a turns. Straightforward, heals the given amount for that amount of turns. Stacks, so you can feasibly heal most of your HP every turn. These skills do not heal you on casting, only on subsequent turns.

Heal instantly: Take the form of heal n% HP. No duration, simply heals the amount of HP given.