Cast Wren's Run Packmaster by paying its mana cost.
When Wren's Run Packmaster enters the battlefield, its champion ability and Molten Echoes triggers.
Resolve the Molten Echoes trigger, creating a token copy of Wren's Run Packmaster with haste.
When the Wren's Run Packmaster token enters the battlefiled, its champion ability triggers, exiling the nontoken Wren's Run Packmaster until the token Wren's Run Packmaster leaves the battlefield.
Resolve the champion ability from step 2, exiling the token Wren's Run Packmaster.
The token Wren's Run Packmaster leaves the battlefield, returning the nontoken Wren's Run Packmaster from exile to the battlefield.
Repeat from step 2.

Infinite creature LTB

Infinite creature ETB

Molten Echoes

Wren's Run Packmaster

Activate Wren's Run Packmaster by paying {2}{G}, creating a 2/2 Wolf creature token as well as a Food, a Clue and a Treasure artifact token.
Activate the Food, Clue and Treasure by tapping them, adding {G}{G}{G}.
Repeat.

Infinite artifact ETB

Infinite artifact tokens

Infinite creature tokens

Infinite tapped Clue tokens

Infinite tapped Food tokens

Infinite tapped Treasure tokens

Infinite card draw

Infinite draw triggers

Infinite Food tokens

Jaheira, Friend of the Forest

Peregrin Took

Academy Manufactor

Activate Wren's Run Packmaster by paying {G} due to Agatha of the Vile Cauldron, creating a 2/2 Wolf creature token.
Activate Phyrexian Altar by sacrificing the Wolf, adding {G}.
Repeat.

Infinite death triggers

Infinite creature sacrifice triggers

Agatha of the Vile Cauldron

Phyrexian Altar

Tap Sunstrike Legionnaire to add {G}.
Pay {G} to create a 2/2 Wolf token.
Sunstrike Legionnaire triggers, untapping.
Repeat.

Combos with "Wren's Run Packmaster"