Basri's Lieutenant, Serra Redeemer, and Phyrexian Altar

Prerequisites

• Basri's Lieutenant on the battlefield
• Serra Redeemer on the battlefield
• Phyrexian Altar on the battlefield
• You control at least one additional creature with a +1/+1 counter on it

Steps

1. Activate Phyrexian Altar by sacrificing another creature with a +1/+1 counter on it, adding one mana of any color
2. The creature dies, triggering Basri's Lieutenant's second ability, creating a 2/2 Knight creature token
3. When the Knight enters the battlefield, Serra Redeemer triggers, putting two +1/+1 counters on the Knight
4. Repeat

Results

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