Bloodspore Thrinax has at least five +1/+1 counters on it.
Steps
At the beginning of your end step, Conjurer's Closet triggers, blinking Sage of Hours and causing it to enter the battlefield with five or more +1/+1 counters on it due to Bloodspore Thrinax.
Activate Sage of Hours by removing all +1/+1 counters from it, causing you to take at least one extra turn after this one.