Ability and stats

If an ability says gain X% attack, does it mean the unmodded atk or current attack value of the creature. Is the artifact stat counted in?

When there are 2 abilities that reduce damage, do they stack or activate sequentially? What about dodge abilities?

Gain x% attack is applied to your entire attack in combat afaik (already modded attack including artifact).

Almost all sources of dodge is separately rolled and damage reduction is multiplicative, not additative.

15% dodge per direwolf = 3 chances to roll for a dodge with 15% chance each time.

All your creatures take 25% less damage. If you have 4 of these you would get 1-0.750.750.75*0.75 = 68% damage reduction)

Alright thanks.

Is initiative determined by speed alone or is there a speed + variance? Also after a creature act, is it moved to the bottom of the queue regardless of its speed?

Speed alone.

There are abilities that manipulate turn order, but barring those you are always placed last in the action order. Speed does not make your turn “come faster”, it just places you in a higher slot on the initial turn order and scales damage slightly.