Heidar, Rimewind Master + Intruder Alarm + Dual Nature + Ashnod's Altar + Shield Sphere

Heidar, Rimewind Master

Intruder Alarm

Dual Nature

Ashnod's Altar

Shield Sphere

How it works

1. Cast Shield Sphere by paying 0.
2. When Shield Sphere enters the battlefield, Intruder Alarm and Dual Nature's first ability triggers.
3. Resolve the Intruder Alarm trigger, untapping all creatures.
4. Resolve the Dual Nature trigger, creating a token copy of Shield Sphere.
5. Activate Ashnod's Altar by sacrificing the Shield Sphere token, adding CC.
6. Activate Heidar by paying 2 and tapping it, returning Shield Sphere to your hand from the battlefield.
7. Dual Nature's second ability triggers, exiling nothing.
8. Repeat.