Talk:List of Answer Skills/@comment-24850617-20140520181029/@comment-1465604-20140603005031

AS Boosts work like this:

They boost a spirit's attack by their Base ATK * Amount of Boost. Let's say you team up a water spirit with 2000 ATK with Sakuya. They will inflict [2000 / 2 * Elemental Multiplier * 0.2] more damage. The bonus damage is separate from all other multipliers. In other words, if the 2000 ATK spirit is a Reverse Ender, the formula for their attack will be [(2000 / 2 * Elemental Multiplier * 1.25) + (2000 / 2 * Elemental Multiplier * 0.2)]. The same goes for Special Skill attack boosters.

So... stacking a 2000 ATK water spirit with Sakuyas will tack on 150 damage against fire spirits per hit and per Sakuya in your deck. I personally confirmed all of this on version 1.3.8, back when we didn't have damage deviation muddling up our tests.