Activate Viscera Seer by sacrificing Riftsweeper.
Riftsweeper dies, triggering Verdant Succession and Myrkul.
Resolve the Myrkul trigger, causing you to exile Riftsweeper and create a token copy of Riftsweeper that is an enchantment and loses all other card types.
The Riftsweeper token enters the battlefield, shuffling the nontoken Riftsweeper into your library from exile.
Resolve the Verdant Succession trigger from step 2, searching your library for Riftsweeper and putting it onto the battlefield.
Riftsweeper enters the battlefield, shuffling any exiled card into its owner's library.
Resolve the Viscera Seer ability from step 1, causing you to scry 1.
Repeat.

Infinite death triggers

Infinite creature ETB

Infinite creature LTB

Infinite creature sacrifice triggers

Infinite scry 1

Myrkul, Lord of Bones

Verdant Succession

Riftsweeper

Viscera Seer

Activate Ashnod's Altar by sacrificing Riftsweeper, adding {C}{C}.
Riftsweeper dies, triggering Verdant Succession and Myrkul.
Resolve the Myrkul trigger, causing you to exile Riftsweeper and create a token copy of Riftsweeper that is an enchantment and loses all other card types.
The Riftsweeper token enters the battlefield, shuffling the nontoken Riftsweeper into your library from exile.
Resolve the Verdant Succession trigger from step 2, searching your library for Riftsweeper and putting it onto the battlefield.
Riftsweeper enters the battlefield, shuffling any exiled card into its owner's library.
Repeat.

Infinite colorless mana

Ashnod's Altar

Activate Carrion Feeder by sacrificing Riftsweeper.
Riftsweeper dies, triggering Verdant Succession and Myrkul.
Resolve the Myrkul trigger, causing you to exile Riftsweeper and create a token copy of Riftsweeper that is an enchantment and loses all other card types.
The Riftsweeper token enters the battlefield, shuffling the nontoken Riftsweeper into your library from exile.
Resolve the Verdant Succession trigger from step 2, searching your library for Riftsweeper and putting it onto the battlefield.
Riftsweeper enters the battlefield, shuffling any exiled card into its owner's library.
Resolve the Carrion Feeder ability from step 1, putting a +1/+1 counter on it.
Repeat.

Infinite +1/+1 counters on a creature

Carrion Feeder

Activate Phyrexian Altar by sacrificing Riftsweeper, adding one mana of any color.
Riftsweeper dies, triggering Verdant Succession and Myrkul.
Resolve the Myrkul trigger, causing you to exile Riftsweeper and create a token copy of Riftsweeper that is an enchantment and loses all other card types.
The Riftsweeper token enters the battlefield, shuffling the nontoken Riftsweeper into your library from exile.
Resolve the Verdant Succession trigger from step 2, searching your library for Riftsweeper and putting it onto the battlefield.
Riftsweeper enters the battlefield, shuffling any exiled card into its owner's library.
Repeat.

Infinite colored mana

Phyrexian Altar

Declare Varragoth as an attacker.
Activate Varragoth by paying {1}{B}, searching your library for Draco, then shuffling your library and putting Draco on top of it.
During the next upkeep, Timesifter triggers, exiling Draco and causing you to get an extra turn after this one.
Activate Emiel by paying {3}, blinking Riftsweeper.
Riftsweeper enters the battlefield, shuffling Draco from exile into your library.
Repeat.

Infinite turns

Lock

Varragoth, Bloodsky Sire

Timesifter

Emiel the Blessed

Draco

Declare Varragoth as an attacker.
Activate Varragoth by paying {1}{B}, searching your library for Draco, then shuffling your library and putting Draco on top of it.
During the next upkeep, Timesifter triggers, exiling Draco and causing you to get an extra turn after this one.
Activate Eldrazi Displacer by paying {2}{C}, blinking Riftsweeper.
Riftsweeper enters the battlefield, shuffling Draco from exile into your library.
Repeat.

Combos with "Riftsweeper"