Lorthos, the Tidemaker

The body is the down payment; the trigger is where the real bill comes due. Cast it for eight, and you have an 8/8 with no evasion and no protection, a body most decks can chump or trade with all day. The game only changes the turn you attack with eight more mana floating, at which point the optional payment buys a mass tap-down: up to eight permanents frozen through their controllers' next untap step. This is not removal. Nothing dies. What it deletes is the option to respond. Tap eight blockers and the swing connects clean; tap a defender's lands and they spend a turn locked out of their own mana; tap their bombs before they ever wake up. The trigger fires on declare, so the board is already cleared by the time damage resolves, and routing the finish through an attack rather than an enters-the-battlefield burst is what makes that timing matter. Most blue threats of this weight win by presenting evasion or hexproof and trusting the clock; this one declines the clock entirely and instead pays a steep optional tax to manufacture one uncontested turn. That gating is the leash on the 8/8: the payoff scales with how much mana you can spare, so it reads as a vanity fatty right up until you can afford both the cast and the freeze and it ends the game in a single swing.