Back during the X&Y era, Yveltal was a hugely popular attacker because of its capability to build up to OHKO anything through Evil Ball
While we have more than enough actual slivers to choose from, there are a few changeling cards that might be considered: Mutavault, Shields of Velis Vel, Amoeboid Changeling, Blades of Velis Vel, Shapesharer, Mirror Entity, Taurean Mauler, Chameleon Colossus
No one is quite sure how that happened, but you could get a 3/3 for three mana with a minimal drawback and the ability to hide from removal
Sokka can attack without tapping, which allows it to also block next turn, and as long as it doesn't attack alone, you can also draw a card
(10/2/2025) You may target a land that is already a creature, perhaps because of a previous earthbend ability
When you summon Orichalcos Kyutora, you will have to pay 500 life points