Burrow skill would cost 
. Would not remove passive abilities. (only those that would have to be removed by necessity of having only 1 activated ability)
As an fyi, when a creature burrows, its skill typically changes to have a cost of 0. I.e. it only costs quanta to burrow a creature, not unburrow it.
Forcing an unburrow cost would definitely make for an interesting option here. I think it would be waranted as an exception since the end effect is that you would halve the attack power of the creature unless the opponent has
quanta on hand.
I'm not sure how hard or easy that would be to code in, but it makes for a fun concept.
P.S. I think quicksand fits better here than for upgraded earthquake myself. Not sure why that name was chosen for that card... Maybe Zanz would be willing to change it, though, so you could make a note in the card notes section. You never know
.
At any rate, at least this way you have an alternative already picked out.
