Metallic Mimic adds some real tribal value in an all colorless deck, since everything but
Scrapheap Scrounger
is an Eldrazi. Those counters really add up, especially if you can chain multiples on the board.
Eldrazi Mimic grows every turn and is at least a 3/2 most of the time. And, because Metallic Mimic causes all Eldrazi to ETB with the counter already on them, the Mimic sees that additional power and will copy it in addition to their base power and toughness.
Eternal Scourge
can trigger Eldrazi Mimic repeatedly if targeted by removal and is amazing exile fodder for
Scrapheap Scrounger
. Most of the time players just won't try to remove it because it's card disadvantage and it causes the spell to fizzle: Unlicensed Disintegration will do no damage, Harnessed Lightning will grant no energy, etc. The Scrounger can also trigger Eldrazi Mimic at Instant-speed when it comes from the graveyard.
Matter Reshaper
is pure value here, since over half of our deck is non-land permanents CMC 3 or lower (roughly 57% of our non-land cards.) But don't forget - this hits lands too, so that brings the total number of targets to around 75% of our deck. Whenever the worst case scenario is "draw a card that you have the mana for", you know it's good.
Thought-Knot Seer probably doesn't need much of explanation, because the card is bonkers. The exile clause here is important because of Delirium and graveyard strategies, plus opposing Scrapheap Scroungers. Metallic Mimic on board makes it dodge Grasp of Darkness and Aether Hub+Harnessed Lightning.
Reality Smasher is amazing. Provides card disadvantage to the opponent if they try to get rid of it, swings aggressively with either Mimic, gets through blockers like a champ... It's everything you want on turn five play and makes for an amazing top deck late game.
Walker of the Wastes is the biggest reason for running a Wastes deck. Dropping a 9/9 Trampler on turn 5 is nuts, and if you have at least one Eldrazi Mimic on the board you can swing for 9 right then and there. It also gives late game land draws a small amount of relevance.
