Omarthis, Ghostfire Initiate
The color line does the structural work here: a colorless creature that only cares about other colorless creatures, an axis narrow enough to define an entire deck around artifacts, Eldrazi, and the occasional devoid body. The cost means the thing arrives as a counter-pile whose size is the whole plan, because the death trigger converts every counter into a manifested card from your library. The counters here are doing double duty: they are stats while the creature lives, and stored cards waiting to hit the battlefield face-down the moment it dies. The middle ability is quieter than it looks. It does not multiply anything; it adds a single counter to itself each time another colorless creature receives one or more, a slow accretion that turns any counter-spreading engine in the deck into fuel for the eventual manifest payout. Read together, the three lines invert the usual reluctance to let a value engine die: death is not a loss but the trigger that cashes every stored counter into a wide board of face-down 2/2s, some of them creatures you can turn up for real. This treats the colorless shell as a tribe in its own right, and it hands that shell a snowball that pays out biggest precisely when it is destroyed.
