Astral Dragon + Oblivion Ring

Astral Dragon
Oblivion Ring

Requires
Astral Dragon in hand. Oblivion Ring on the battlefield. 6uu available.
Steps
  1. Cast Astral Dragon by paying 6uu
  2. Astral Dragon enters the battlefield, creating two token copies of Oblivion Ring that are 3/3 Dragons in addition to their other types
  3. The Oblivion Ring tokens enter the battlefield, triggering their first abilities
  4. Resolve the first Oblivion Ring token's trigger, exiling Astral Dragon
  5. Resolve the second Oblivion Ring token's trigger, exiling the first Oblivion Ring token
  6. The first Oblivion Ring token leaves the battlefield, returning Astral Dragon from exile to the battlefield
  7. Repeat from step 2
Results
Infinite creature tokens. Infinite copies of noncreature permanents you control. Infinite ETB. Infinite LTB.