The Payoff
"Mills the opponent's entire library (one-sided deck-out)"
Requirements
Goblin Welder
Phyrexian Devourer
Altar of Dementia
The Combo: Storyboard
Step 1
Get Phyrexian Devourer onto the battlefield. Goblin Welder can weld it in from the graveyard, sacrificing a spare artifact, so it never has to be hard-cast.
Step 2
Activate Phyrexian Devourer, exiling cards from the top of your library to pile on +1/+1 counters. Hold priority while its sacrifice trigger (power 7+) is on the stack.
Step 3
In response, sacrifice Phyrexian Devourer to Altar of Dementia, milling the opponent for a number of cards equal to the Devourer's now-enormous power.
Step 4
Mill the opponent's entire library; they lose on their next draw.
⚠ Rules Note
Phyrexian Devourer's triggered ability sacrifices it once its power reaches 7 or greater, so you must respond to that trigger (or sacrifice it to the Altar with the trigger on the stack) before it dies on its own, so you keep the accumulated power for the Altar's mill. Goblin Welder is the resilient enabler here: it recurs the Devourer from the graveyard and dodges artifact removal.