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

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Weatherseed Treefolk

Sneak Attack

Phyrexian Altar

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

Combos with "Weatherseed Treefolk"