Ozimandus, Creation of Dragons

Persist

Whenever you cast an instant or sorcery spell, put a +1/+1 counter on Guthrie.

Draconic Form - At the beginning of your end step, if Guthrie has 20 or more +1/+1 counters on him, Guthrie becomes Tissus Reborn, a 10/10 legendary dragon artifact creature with flying and indestructible.