Dark Sphere + Doubling Season Combos

Combo 1 with Tamiyo, the Moon Sage

Steps

1. Cast Tamiyo by paying {3}{U}{U}. Tamiyo enters the battlefield with eight loyalty counters on it due to Doubling Season.
2. Activate Tamiyo's third loyalty ability by removing eight loyalty counters from it, causing you to get its emblem.
3. Cast Dark Sphere by paying {0}.
4. Activate Dark Sphere by tapping and sacrificing it.
5. Tamiyo's emblem triggers, returning Dark Sphere from your graveyard to your hand.
6. Repeat from step 3.