Whim of Volrath with buyback by paying ({2} magic symbol) ({U} magic symbol) , returning it to your hand.
At the beginning of your combat phase,
The Thing's first ability triggers, putting four +1/+1 counters on it.
Declare
The Thing as an attacker. Its second ability triggers, causing you to pay ({R} magic symbol) ({G} magic symbol) ({W} magic symbol) ({U} magic symbol) to double the number of +1/+1 counters on it.
Activate
The Thing using
Sage of Hours' ability by removing all +1/+1 counters from it, causing you to take an extra turn after this one.
Repeat each turn.
Notes
You can cast any noncreature spell in lieu of
Whim of Volrath.
Whim of Volrath is strongly recommended as it guarantees you can cast a noncreature spell each turn, but you may omit it at your discretion.