Goldberry, River-Daughter, Thornbite Staff, Phyrexian Altar, Intruder Alarm, and Geralf's Mindcrusher

Prerequisites

• Goldberry, River-Daughter on the battlefield
• Thornbite Staff on the battlefield
• Phyrexian Altar on the battlefield
• Intruder Alarm on the battlefield
• Geralf's Mindcrusher on the battlefield
• Thornbite Staff attached to Goldberry
• Goldberry does not have summoning sickness
• Goldberry and Geralf's Mindcrusher do not have a +1/+1 counter on it

Steps

1. Activate Phyrexian Altar by sacrificing Geralf's Mindcrusher, adding
2. When Geralf's Mindcrusher dies, its undying ability and Goldberry trigger
3. Resolve the Geralf's Mindcrusher trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it
4. When Geralf's Mindcrusher enters the battlefield, it and Intruder Alarm triggers
5. Resolve the Geralf's Mindcrusher trigger, causing a player to mill five cards
6. Resolve the Intruder Alarm trigger, untapping all creatures
7. Holding priority, activate Goldberry's first ability by tapping it, moving the +1/+1 counter from Geralf's Mindcrusher onto Goldberry
8. Resolve the Goldberry trigger from step 2, untapping it
9. Activate Goldberry's second ability by paying and tapping it, moving the +1/+1 counter from Goldberry onto any permanent except Geralf's Mindcrusher, and causing you to draw a card
10. Repeat

Results

• Infinite card draw
• Infinite draw triggers
• Near-infinite +1/+1 counters
• Near-infinite death triggers
• Near-infinite ETB
• Near-infinite LTB
• Near-infinite mill
• Near-infinite sacrifice triggers
• Near-infinite untap of all creatures