Jan Jansen, Chaos Crafter, Haunted One, Retribution of the Ancients, and Phyrexian Altar

Prerequisites

• Jan Jansen, Chaos Crafter on the battlefield
• Haunted One on the battlefield
• Retribution of the Ancients on the battlefield
• Phyrexian Altar on the battlefield
• Jan Jansen and the additional Gnome or Artificer do not have a +1/+1 counter on them
• You control at least one additional artifact creature

Steps

1. Activate Jan Jansen's first ability by tapping it and sacrificing another artifact creature you control except the Gnome or Artificer
2. Jan Jansen triggers, causing it and creatures you control that share a creature type with it to get +2/+0 and undying until end of turn
3. Resolve the Jan Jansen ability, creating two Treasure tokens
4. Activate Phyrexian Altar by sacrificing Jan Jansen, adding
5. When Jan Jansen dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
6. Activate Jan Jansen's first ability by tapping it and sacrificing the Gnome or Artificer
7. When the Gnome or Artificer dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
8. Resolve the Jan Jansen ability, creating two Treasure tokens
9. Activate Retribution of the Ancients by paying and removing the +1/+1 counter from Jan Jansen and the other Gnome or Artificer, giving a creature -2/-2 until end of turn
10. Repeat from step 4

Results

• Infinite LTB
• Infinite ETB
• Infinite colored mana
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite Treasure tokens
• Reduce any number of target creatures' toughness to zero
• All other Artificers you control are infinitely powerful until end of turn
• All other Gnomes you control are infinitely powerful until end of turn