Skeleton Ship + Intruder Alarm + Geralf's Mindcrusher + Woe Strider

Skeleton Ship

Intruder Alarm

Geralf's Mindcrusher

Woe Strider

How it works

1. Activate Woe Strider by sacrificing Geralf's Mindcrusher.
2. Geralf's Mindcrusher dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
3. Geralf's Mindcrusher enters the battlefield, triggering itself and Intruder Alarm.
4. Resolve the Geralf's Mindcrusher trigger, causing target player to mill five cards.
5. Resolve the Intruder Alarm trigger, untapping all creatures.
6. Resolve the Woe Strider ability from step 1, causing you to scry 1.
7. Activate Skeleton Ship by tapping it, putting a -1/-1 counter on Geralf's Mindcrusher.
8. Repeat.

This crafty loop relies on Woe Strider to feed Geralf's Mindcrusher to the graveyard, where its undying ability rescues it and returns it to the battlefield with a +1/+1 counter. Every time Geralf's Mindcrusher enters, Intruder Alarm triggers to untap all your creatures, letting you use Skeleton Ship to place a -1/-1 counter on Geralf's Mindcrusher, which neutralizes its existing +1/+1 counter so the undying trigger can work all over again. As this cycle repeats, Woe Strider lets you scry through your library while milling out your opponent completely.