Naru Meha, Master Wizard

Flash is the entire point, and it lives on the creature, not the copy. Cast her at instant speed and her enter-the-battlefield trigger copies a spell you control, choosing new targets: that copy can be a flicker effect that blinks her right back to the battlefield, re-firing the trigger for free and copying the flicker again. That is the loop she completes. Ghostly Flicker plus a second permanent to blink, and she becomes a self-sustaining engine that repeats that flicker arbitrarily many times without touching her mana cost again. The Wizard lord clause, the +1/+1 to your other Wizards, is tribal decoration and reads that way; nobody assembles a four-mana copy engine for the anthem. What earns the legendary tag is the timing. Because she flashes in, the spell you want doubled can be answered on the same stack, held up as insurance against removal, or fired in response to an opponent's play rather than on your own main phase. A copy stapled to a plain sorcery-speed body would be locked to your turn and telegraphed a step in advance; flash collapses that window, letting the whole sequence happen at the moment of your choosing. The 3/3 is incidental. She exists to turn a single instant or sorcery into as many resolutions as your loop can support, and to do it in the enemy's step if that is where the leverage is.