Activate Viscera Seer by sacrificing Arcbound Prototype.
When Arcbound Prototype dies, its modular ability and persist ability trigger.
Resolve the modular trigger, putting Arcbound Prototype's +1/+1 counters on another artifact creature.
Resolve the persist trigger, returning Arcbound Prototype from your graveyard to the battlefield. It will not have a -1/-1 counter on it due to its modular ability.
Resolve the Viscera Seer ability.
Repeat.

Infinite artifact ETB

Infinite artifact LTB

Infinite artifact sacrifice triggers

Infinite creature LTB

Infinite creature ETB

Infinite creature sacrifice triggers

Infinite death triggers

Infinite scry 1

Infinite +1/+1 counters on certain creatures

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

Viscera Seer

Arcbound Prototype

Activate Antler Skulkin by paying {2}, giving Arcbound Prototype persist until end of turn.
Activate Ashnod's Altar by sacrificing Arcbound Prototype, adding {C}{C}.
When Arcbound Prototype dies, its modular and persist abilities trigger.
Resolve the modular trigger, putting all +1/+1 counters on Arcbound Prototype onto another artifact creature you control.
Resolve the persist trigger, returning Arcbound Prototype from your graveyard to the battlefield with one +1/+1 counter on it due to its modular ability.
Repeat.

Antler Skulkin

Ashnod's Altar

Activate Antler Skulkin by paying {2}, giving Arcbound Prototype persist until end of turn.
Activate Krark-Clan Ironworks by sacrificing Arcbound Prototype, adding {C}{C}.
When Arcbound Prototype dies, its modular and persist abilities trigger.
Resolve the modular trigger, putting all +1/+1 counters on Arcbound Prototype onto another artifact creature you control.
Resolve the persist trigger, returning Arcbound Prototype from your graveyard to the battlefield with one +1/+1 counter on it due to its modular ability.
Repeat.

Krark-Clan Ironworks

Activate Arcbound Prototype by paying {1}{U}, blinking it.
Arcbound Prototype leaves and reenters the battlefield, causing it to enter with +1/+1 counters due to its modular ability, and triggering The Ooze and Deadeye Navigator's soulbond ability.
Resolve Deadeye Navigator's trigger, repairing it and Arcbound Prototype
Resolve The Ooze's trigger, creating a Mutagen token for each +1/+1 counter that was on Arcbound Prototype when it left the battlefield.
Activate Urza's first ability twice by tapping Arcbound Prototype and a Mutagen, adding {U}{U}.
Repeat.

Combos with "Arcbound Prototype"