At its most basic, this is a 3/3 for 3 mana that lets you cast creatures from the top of your library
Welder Automaton: Good in Limited, also in multiplayer Two-Headed Giant
With offspring, that's two damage, and it's easy to see where this is going - it's an alternate win condition in grindy games and its unearth ability means it can come back to provide that effect for one extra turn whenever it's most relevant
But commander players know better, and are now using this Clever Conductor to perform the following game winning combo: Play Toluz, Clever Conductor and connive
Hydreigon 140/193 Loading
Of course, you need to pay for that 12 power somewhere , which has inspired Legacy decks that play Phyrexian Dreadnought to cheat it in on turn 2 with a Stifle