Thundermare

Cast this spell only during the declare blockers step. X target attacking creatures become blocked. Choking Vines deals 1 damage to each of those creatures. (This spell works on creatures that can't be blocked.)

T, Sacrifice this creature: Untap all Forests.

This creature enters with four shell counters on it. At the beginning of your upkeep, remove a shell counter from this creature. As long as this creature has no shell counters on it, it gets +3/+2 and has flying.

Cumulative upkeep 2 (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.) When a player doesn't pay this enchantment's cumulative upkeep, this enchantment deals X damage to target player or planeswalker and each creature that player or that planeswalker's controller controls, where X is twice the number of age counters on this enchantment minus 2.

WW, T: Destroy target red permanent.

Flying When another creature enters, return this creature to its owner's hand.

Flying Pay 1 life: Regenerate this creature.