Hydra Cards Reduction

[Zaratus]

Base atk from weap+refine atk+dex atk+str atk+several other atk bonuses (including weapon masteries) are all affected by cards.

Also, you got a mistake right now in your post there.

Shikari Wrote:Skell worker (base attack is now 105 because of its bonus) adds 15.75 dmg
1st hydra adds 20 dmg
2nd hydra adds 20 dmg
total->160.75

The hydras take the new base atk, 105.

What split means is that if you have 2 hydra cards and 100 atk, the first hydra card adds 20 % dmg [100->120] but the second only 16.67 % [120->140]. The third one adds 14.29 % [140->160]. The fourth one adds 12.5 % [160->180]. That's what they mean with the effect being "reduced" since it only works on base atk, not the effective one. All in all it's a 80 % damage increase though.

Skel Worker and 2 Hydras with 100 atk look like that. Skel Worker boosts to 105 atk. Skel Worker +15 % [105->120.75]. Two Hydras add 40 % [120.75->169.05].
3 Hydras are "just" +60 % [100->160].

I hope this clears stuff up a bit.