Yedora, Grave Gardener, Phyrexian Altar, and Horde Ambusher

Prerequisites

• Yedora, Grave Gardener on the battlefield
• Phyrexian Altar on the battlefield
• Horde Ambusher on the battlefield
• You have at least one red card in hand

Steps

1. Activate Phyrexian Altar by sacrificing Horde Ambusher, adding one mana of any color
2. When Horde Ambusher dies, Yedora triggers, returning Horde Ambusher from your graveyard to the battlefield face down as a Forest land
3. Activate Horde Ambusher's morph ability by revealing a red card from your hand, turning it face up
4. Repeat

Results

• Infinite colored mana
• Infinite death triggers
• Infinite landfall triggers
• Infinite LTB
• Infinite sacrifice triggers