Interesting ideas!
Re:
Forest Clearing - You have a 5-turn mini-Cloak for 2
|1
. A regular 3-turn full Cloak sells for 4
|3
. I think your card should cost about the same as Cloak. Forest Clearing gives up protecting permanents, but it takes it back in turns.
Re:
Collapsing Golem - Cool implementation. Best played in the absence of cards that hasten your draw, obviously, so that means that the creature will last for 8|12 turns, assuming it receives no damage. 3
|3
may be enough, considering that the HP drops at least once per turn. It just feels too inexpensive to me.
Re:
Anachronistic Poison - Costs less than Heal, so it probably comes on your second turn. Even if the opponent has no PC, it still takes ten turns to equal Heal. So yeah, that sounds balanced. If the duel goes longer than 12 turns, you're gonna need it!
Nicely done.