Lightning Runner + Cursed Mirror + Wulfgar of Icewind Dale

Lightning Runner

Cursed Mirror

Wulfgar of Icewind Dale

How it works

1. Attack with both Lightning Runners.
2. Both Lightning Runners trigger twice.
3. Resolve the first three triggers, adding EEEEEE and chosing not to pay the trigger.
4. Resolve the fourth trigger, adding EE and pay EEEEEEEE to untap all creatures you control, and after this phase, there is an additional combat phase.
5. Repeat.