Three mana, evasionless, two toughness: that body dies to every common removal spell in the format and trades down into the 
2/3 commons that fill out every midrange curve. The card is sold on the trigger, and the trigger only fires if the rest of the deck has already built a board worth copying. UR Artifacts is the only home that makes the math work. There, the Sneak cost is a feature: you turn an unblocked attacker into a tapped, attacking Donatello, the original threat snaps back to hand for a redeploy, and the copy lands on an Equipment, a mana rock, or a Food. In any other blue deck this is a 3/2 for three that asks you to give up locked-in damage to maybe untap with a fragile copy engine.
The pick band tracks that narrowness. P1P5 to P1P7 if you have already signaled UR and watched an artifact payoff wheel; P1P8 or later in any other blue seat, where it should sit out of your 40 entirely. Bespoke Bō is the cleanest target in the format: a copied Equipment immediately suits up a second attacker for the next Sneak loop, and Novel Nunchaku rewards the same pattern. The punisher is Grounded for Life. Donatello enters tapped off Sneak, which is exactly the window where the white common is cheapest, so any white deck on the draw can break the engine before it triggers once.
GU Tempo can cast him, but without artifact density the copy clause is dead text and you are paying full price for a 3/2 that wants to be on offense. He is a build-around masquerading as a curve filler, and the build is narrow enough that most blue drafters will never assemble it.
