I've been wondering for a while now: Why have your mark appear as a card when its impossible to summon?
Thus, i had the idea of being able to play a mark. IMO, the mark should have one of 2 affects:
1:Change your mark
2: Change the element of the target card in your hand
ex: use "Mark of

" to make Earthquake cost 3

instead of 3

Just thought it would be interesting to see what other people think.