Stalwart Successor, Phyrexian Altar, and Kithkin Spellduster

Prerequisites

• Stalwart Successor on the battlefield
• Phyrexian Altar on the battlefield
• Kithkin Spellduster on the battlefield

Steps

1. Activate Phyrexian Altar by sacrificing Kithkin Spellduster When Kithkin Spellduster dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
2. When Kithkin Spellduster enters, Stalwart Successor triggers, putting a +1/+1 counter on Kithkin Spellduster Repeat

Results

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