First: I suggest to reduce the cost of Tunneling by 2 in upped and unupped.
Reasoning:
1, Most of the time it's better to let your creatures unburrowed. Yes, it's like auto-win against Dim shield spam, but in general, you don't really want to play with a card what does something if the opponent has a shield, neither player has PC and it's worthy to halve your creature's attack to avoid the shield's effect.
2, There's not that much card to use with and it's not that effective with them. Graboid 1 dmg per turn for 3
, Antlion 2 dmg per turn for 3
and Shrieker 5 dmg per turn for 9
(or for 4
+
and 2 turn). And 2,5 card combos to sink your own creatures to evade shields.
3, You don't only pay 3|4, but 1
for every creature you want to be burrowed, so it's cost mostly 7-8 quanta to be effective.
Second: Upped Sinkhole should cost only 1
, but giving "
: unburrow" as the unupped. Unburrowing from Sinkhole should cost 0, if cast on
creature.
Reasoning: if the opponent has earth quanta, in most cases it's will be more than enough to unburrow the creature without causing mayor problems to the player, so there's no real difference between the unupped and the upped. The second sentence to give some additonal option to use on your creatures as well.