Achievement Forest
Unlock Character Cryptid

My recommend character is the explorer with stick.
Since the explorer have stat more tree spawn.
But he spawn with lumberjack shirt that have ability to destroy tree in 1 hit that mean you should avoid all item and weapon that granted projectiles.
For weapon you can use any melee weapons because long range weapon may unintentionally target trees.

Try to gather item that grant you luck or bonus tree items and try not to go near trees as much as you can. If you keep do it you might finish in wave 5 or 6.

If you are lucky enough, you can finish it in the second wave.