Source: http://win.wizkids.com/bb/viewtopic....cf3d0aba7deca8

MYSTICS - Each time this character takes damage from an opposing character's attack, after resolutions deal the attacker 1 penetrating damage. Uncopyable.

If a character takes damage due to the Mystics team ability, is it considered to have been "damaged" by the character using the Mystics team ability for effects that check to see if a character has been damaged by an opposing character?

WK: Yes. Damage dealt by the Mystics team ability is damage being dealt from the character with that team ability and may possibly trigger effects that look for a character being damaged by another character (depending on the wording of the effect).