Pebbles, Fungal Guardian

Protection from creatures
Whenever a creature dies, put a spore counter on Pebbles.
Remove a spore counter from Pebbles: Create
a 1/1 green Saproling creature token.
At the beginning of your upkeep, if there are 6
or more spore counters on Pebbles, transform it
into "Pebbles, Rotwood Behemoth".
At the start of your next turn, remove all spore counters from Pebbles and revert the transformation.