Legate Lanius, Caesar's Ace

Decimate appears in italics here as a flavor word, not a Magic keyword, and the effect it names is strictly one-sided: only opponents lose creatures, and the rounding rule is where the real design lives. Against a board of one to ten creatures the entry trigger takes exactly one; it can wipe a lone blocker outright yet only chips at wide boards, and it scales without ever demanding a token count. That proportionality is what keeps a 2/2 for four in check: nothing happens to an empty board, and the effect grows only against an opponent who has committed a real one. The second ability turns those sacrifices into growth, and it reads more broadly than the trigger that feeds it: any opponent sacrificing a creature for any reason, not just from the entry effect, adds a +1/+1 counter. That opens a build-around axis outside the enters trigger entirely, where edicts and group-wide sacrifice effects that force opponents to sacrifice all feed the counters, and each one landed makes the body a genuine clock rather than a fragile value creature. The synthesis is a Rakdos midrange threat that picks off a key blocker on the way in, then converts that punishment into a self-growing beater, with the rounding rule doing the quiet work of making a small one-sided trigger bite hardest exactly when an opponent leans on a single tall creature.