Umbris gets +1/+1 for each card your opponents own in exile.
Whenever Umbris or another Nightmare or Horror you control enters, target opponent exiles cards from the top of their library until they exile a land card.
Umbris turns opponents' libraries into fuel: every Nightmare or Horror ETB exiles cards off a target opponent's library until a land hits, growing Umbris and shrinking decks toward an empty-library loss. You voltron Umbris into a quickly-lethal commander beater while flooding the board with cheap Nightmares/Horrors to chain exile triggers, eventually milling everyone out or swinging for a giant connection.
Umbris snowballs into a massive, evasive threat with minimal investment
Exiling lands draws opponents closer to deck-out, a hard-to-interact-with win
Tons of cheap Nightmares and Horrors trigger the ETB repeatedly
Blink and recursion give nearly limitless exile triggers
Removal-dependent: Umbris dies and the board pressure collapses fast
No built-in evasion or protection on the commander
Exiling lands accelerates opponents to their bombs early
Slow to actually kill a table of three opponents via deck-out without acceleration
Lets you cast and recast cheap Nightmares/Horrors for free to chain exile triggers.
Add evasion and protection—Whispersilk Cloak, Rogue's Passage, Swiftfoot Boots—so Umbris reliably connects and survives spot removal. Lean into blink (Conjurer's Closet, Ghostly Flicker) and free recursion to multiply exile triggers, and tighten the curve with cheap, value-laden Nightmares/Horrors. Pair processors like Wasteland Strangler and It That Betrays with the exile pile, and run Bloodchief Ascension plus fight/double-strike enablers to give yourself redundant, faster wins.
Legendary Creature — Nightmare Horror
