DevoidDevoid is a characteristic-defining ability. “Devoid” means “This object is colorless.” This ability functions everywhere, even outside the game. See rule 604.3. (CR 702.114) (This card has no color.)
MenaceMenace is an evasion ability.
A creature with menace can’t be blocked except by two or more creatures. (See rule 509, “Declare Blockers Step.”)
Multiple instances of menace on the same creature are redundant. (CR 702.111)
Whenever this creature deals combat damage to a player, that player exiles cards from the top of their library until they
exileTo exile an object, move it to the exile zone from wherever it is. See rule 406, “Exile.” (CR 701.13) a nonland card. You may
castTo cast a spell is to take it from the zone it’s in (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect. A player may cast a spell if they have priority. See rule 601, “Casting Spells.”
To cast a card is to cast it as a spell. (CR 701.5) that card by paying life equal to the spell's mana value rather than paying its mana cost.