Vampiric Aura/Critical Strike/Acrobatics Bug

So I’m not sure if this is a bug with Always having Critical, Vampiric Aura, Acrobatics or all of them combined…

If an enemy drains your attack to 0, your creatures can still “Crit” for damage (usually like 50) this may be, due to the fact Acrobatics makes them use some speed instead of Attack, so their attack isn’t a 0, however. Vampiric Aura heals for 0 when this occurs, I’m not sure if this is intended or not.