Elenda, the Dusk Rose, Felisa, Fang of Silverquill, and Phyrexian Altar

Prerequisites

• Elenda, the Dusk Rose on the battlefield
• Felisa, Fang of Silverquill on the battlefield
• Phyrexian Altar on the battlefield
• Elenda has at least three +1/+1 counters on it, plus an additional +1/+1 counter for each time you've cast Elenda from the command zone this game
• plus enough mana to pay for commander tax, if applicable available

Steps

1. Activate Phyrexian Altar by sacrificing Elenda, adding
2. Choose to return Elenda to the command zone from your graveyard
3. Elenda dies, triggering its second ability and Felisa
4. Resolve the Elenda trigger, creating a number of 1/1 Vampire creature tokens equal to Elenda's power
5. Resolve the Felisa trigger, creating a number of 2/1 Inkling creature tokens equal to the number of counters on Elenda
6. Cast Elenda from the command zone by paying and commander tax, if applicable
7. Activate Phyrexian Altar by sacrificing a Vampire or an Inkling, adding
8. The Vampire or Inkling dies, triggering Elenda's first ability, putting a +1/+1 counter on it
9. Repeat from step 7 for each remaining Vampire or Inkling
10. Repeat from step 1

Results

• Infinite +1/+1 counters on Elenda
• Infinite colored mana
• Infinite commander casts
• Infinite creature tokens
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers
• Infinite storm count