Devour 1 (As this creature enters, you may sacrifice any number of creatures. It enters with that many +1/+1 counters on it.)
Each other creature you control enters with an additional X +1/+1 counters on it, where X is the number of +1/+1 counters on this creature.
If Bloodspore Thrinax enters the battlefield at the same time as other creatures you control, those creatures won't get additional +1/+1 counters from Bloodspore Thrinax's last ability. Those creatures also can't be devoured by Bloodspore Thrinax.