u/Old_Introduction1454

I'm asking this question out of curiosity, totally not trying to find a strat for Great Rift

After playing and testing this archetype since Season 3, I've discovered quite a lot and I want to share my knowledge in this post.

First of all, I want to describe all the kind of buffs you can get in order to increase Counterattack Multiplier, then put all of them in a formula to get the final multiplier and visualize how they interact between each other (I'm excluding debuffs on enemies)

1. "+x% Damage Amount to Counterattacks". Right now the only character that can get this effect is Maribell (5th epiphany on Wolves' Dome). Stacks with itself. This buff effectively increases the base Counterattack multiplier, it will be more clear to understand in the formula.
2. "Increase Damage Amount by x% to Counterattacks". Sources of this buff: Starlight and Dreams memory frag set, Victor's Laurel (S2 planet exclusive equipment), Counter Surge from Persona engravings, Erica (partner), Magna's E6, Magna's Ice Fragment epiphany 3rd and 5th. The 5th one offers a bigger buff than the 3rd but only for the next istance of Counterattack, while the 3rd is permanent and, as of now, doesn't stack with itself, probably due to a bug.
3. "Increase Damage Amount by x%". Sources of this buff: Glory's Reign memory frag set, various equipments. The best one is Veiled Thorn (S2 planet exclusive) which gives 50%, but you can't damage enemies with cards or it will lose its effect; it seems that it will lose its effect even with damage that comes from passive abilities that are tied to cards, like Metallization, not sure if it's a bug or innaccurate description (I've only tested with Amir). There's also an equipment refinement on S2 planet which has the same effect as Veiled Thorn, and one that gives 10% to allies if you fully block damage.

Also note this buff is different from the one above, as they multiply each other instead of being additive, which is an huge deal, as it adds an extra multiplicative layer. You'll see this in the formula.

4. Additive buffs. These ones can have slight name variations, but they are effectively the same thing and they will work like Morale. I won't focus on them since they're the least important ones, unless you're using Dominion, which is an infinite ramp on Morale (fuck Dominion).

The formula for the final multiplier is this:

(Base Multiplier + x% Damage Amount to Counterattacks) * (Increase Damage Amount by x% to Counterattacks) * (Increase Damage Amount by x%) + "additive buffs"

Which planet is best to farm for a Counterattack focused deck?

S2 planet if your character/deck has easy access to getting Counterattacks.

S3 planet if your character/deck doesn't. Get a Persona card with Counterattack engravings.

With this knowledge your Magna will mog Hew (Massacre) and get up to 1000% AOE multiplier on every Counterattack.