Activate Ashnod's Altar by sacrificing Dominion Saboteur, adding {C}{C}.
When Dominion Saboteur dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it. Choose to have it enter as a copy of the creature with persist with a +1/+1 counter on it.
Remove a +1/+1 counter and a -1/-1 counter from Dominion Saboteur as a state-based action.
Repeat.

Infinite colorless mana

Infinite creature ETB

Infinite creature LTB

Infinite creature sacrifice triggers

Infinite death triggers

Persist Creature

Dominion Saboteur

Ashnod's Altar

Cast Dominion Saboteur by paying its mana cost, choosing to have it enter the battlefield as a copy of Felidar Guardian
When Dominion Saboteur enters the battlefield, it triggers, blinking Felidar Guardian.
When Felidar Guardian enters the battlefield, it triggers, blinking Dominion Saboteur. Choose to have Dominion Saboteur enter the battlefield as a copy of Felidar Guardian.
Repeat from step 2.

Felidar Guardian

Activate Altar of Dementia by sacrificing Dominion Saboteur.
When Dominion Saboteur dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it. As it enters, choose to have it copy a non-Human you control with a -1/-1 counter on it, and then also enter with a -1/-1 counter on it.
Resolve the Altar of Dementia ability
Repeat.

Infinite mill

Infinite self-mill

Mikaeus, the Unhallowed

Altar of Dementia

Because Dominion Saboteur and Pramikon disagree on the direction in which players can attack, players are unable to attack at all so long as there are three or more players.

Creatures can't attack

Lock

Pramikon, Sky Rampart

Put any nontoken creature onto the battlefield.
When the creature enters, Radiant Solar, Dominion Saboteur and Glasspool Mimic each trigger.
Resolve the Radiant Solar trigger, causing you to venture into Tomb of Annihilation and into the Trapped Entry room, causing each player to lose 1 life.
Resolve the Dominion Saboteur trigger, venturing into the Oubliette room, causing you to discard a card and then sacrifice Radiant Solar.
Resolve the Glasspool Mimic trigger, venturing into the Cradle of the Death God room, creating a 4/4 legendary The Atropal creature token and completing Tomb of Annihilation.
If you control two or more The Atropal tokens, put all but one into your graveyard due to the legend rule.
Sefris' second ability triggers, returning Radiant Solar from your graveyard to the battlefield.
Repeat from step 2.

Near-infinite creature ETB

Near-infinite creature LTB

Near-infinite creature sacrifice triggers

Near-infinite death triggers

Near-infinite lifeloss for all players

Sefris of the Hidden Ways

Radiant Solar

Glasspool Mimic // Glasspool Shore

Activate Dominion Saboteur by paying {1}{U}, shuffling Dominion Saboteur into your library and milling your entire library due to it not having a card named Mirror-Mad Phantasm in it.

Mirror-Mad Phantasm

Activate Grimgrin by sacrificing Dominion Saboteur.
When Dominion Saboteur dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it. As it enters, choose to have it copy a creature you control that has a +1/+1 counter on it, so Dominion Saboteur will also enter with a +1/+1 counter on it.
Resolve the Grimgrin ability.
Repeat.

Infinite +1/+1 counters on a creature

Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight

Grimgrin, Corpse-Born

Activate a mana-producing permanent you control by tapping it, adding at least {G}.
Activate Wayta by paying {G} and tapping it, causing Cacophodon and Bellowing Aegisaur to fight each other, with each only taking 1 damage due to Temple Altisaur.
Cacophodon and Bellowing Aegisaur trigger twice.
Resolve both Bellowing Aegisaur triggers, putting two +1/+1 counters on each creature you control.
Resolve both Cacophodon triggers, untapping the mana-producing permanent and Wayta.
Repeat from step 2, alternating between having Cacophodon fight Bellowing Aegisaur and Dominion Saboteur to ensure neither dies due to lethal damage.

Infinite +1/+1 counters on creatures you control

Wayta, Trainer Prodigy

Bellowing Aegisaur

Cacophodon

Temple Altisaur

Activate Dominion Saboteur by sacrificing it.
When Dominion Saboteur dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it. As it enters, choose to have it copy Aerie Ouphes, and then also enter with a +1/+1 counter on it.
Resolve the Dominion Saboteur ability from step 1.
Repeat.

Aerie Ouphes

Cast Dominion Saboteur by paying its mana cost, choosing to have it enter the battlefield as a copy of Esper Terra that isn't legendary. This will cause it to enter the battlefield with a lore counter as it will be a Saga.
Dominion Saboteur's first chapter ability triggers, creating a token copy of Dominion Saboteur with haste, which will enter as a copy of Esper Terra with haste that isn't legendary and with one to four lore counters on it.
The Dominion Saboteur token's chapter abilities will trigger according to how many lore counters were placed on it.
Resolve the first Dominion Saboteur trigger, creating a token copy of Dominion Saboteur with haste, which will enter as a copy of Esper Terra with haste that isn't legendary and with one to four lore counters on it.
Repeat from step 3.

Combos with "Dominion Saboteur"