Pentavus, Cauldron of Souls, Clock of Omens, and Krark-Clan Ironworks

Prerequisites

• Pentavus on the battlefield
• Cauldron of Souls on the battlefield
• Clock of Omens on the battlefield
• Krark-Clan Ironworks on the battlefield
• Pentavus does not have a -1/-1 counter on it

Steps

1. Activate Cauldron of Souls by tapping it, giving Pentavus persist until end of turn
2. Activate Krark-Clan Ironworks by sacrificing Pentavus, adding
3. When Pentavus dies, its persist ability triggers, returning it from your graveyard to the battlefield with four +1/+1 counters on it
4. Activate Pentavus' first ability twice by paying and removing two +1/+1 counters from it, creating two 1/1 Pentavite artifact creature tokens
5. Activate Clock of Omens by tapping Pentavus and a Pentavite, untapping Cauldron of Souls
6. Repeat
7. Once you have infinite colorless mana and Pentavite tokens, you may use Pentavus' second ability to put infinite +1/+1 counters on it

Results

• Infinite +1/+1 counters on Pentavus
• Infinite colorless mana
• Infinite creature tokens
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana artifacts you control can produce
• Infinite sacrifice triggers
• Infinite untap of artifacts you control