Karn, the Great Creator + Displacer Kitten + Ugin's Nexus + Arcbound Ravager

Karn, the Great Creator
Displacer Kitten
Ugin's Nexus
Arcbound Ravager

Requires
All permanents on the battlefield. Karn has at least three loyalty counters. 5 available on each extra turn.
Steps
  1. Activate Arcbound Ravager by sacrificing Ugin's Nexus
  2. Ugin's Nexus is exiled instead of being put into your graveyard, causing you to take an extra turn after this one
  3. Resolve the Arcbound Ravager ability, putting a +1/+1 counter on it
  4. Activate Karn's second ability by removing two loyalty counters from it, putting Ugin's Nexus into your hand from exile
  5. Move to your next turn
  6. Cast Ugin's Nexus by paying 5
  7. Displacer Kitten triggers, blinking Karn
  8. Repeat
Results
Infinite turns.