Activate Sneak Attack by paying {R}, putting Zodiac Dragon from your hand onto the battlefield.
Activate Phyrexian Altar by sacrificing Zodiac Dragon, adding {R}.
Zodiac Dragon dies, returning itself from your graveyard to your hand.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Zodiac Dragon

Sneak Attack

Phyrexian Altar

Activate Sneak Attack by paying {R}, putting Zodiac Dragon from your hand onto the battlefield.
Activate Thermopod's second ability by sacrificing Zodiac Dragon, adding {R}.
Zodiac Dragon dies, returning itself from your graveyard to your hand.
Repeat.

Combos with "Zodiac Dragon"