Redshift, Rocketeer Chief is a really good commander for a +1/+1 counters deck, or one that care about boosting power with something like Unnatural Growth
A creature "has a hat" if the creature depicted in the art is in possession of a hat
Kardur, Doomscourge - Goad is a fun and powerful mechanic, and while its not specifically called that on the card, thats what this guy does to all your opponents creatures on ETB
There is a lot of crossover potential, and cards that are good in multiple deck archetypes like Bloodghast (good in aggro and Smallpox archetypes) or Snapcaster Mage also work to fill your quota
OP-16 returns to the war that defined One Piece for a generation of fans: Impel Down into Marineford
Any red deck can make room for a copy there aren't many games where you wont have a good opportunity to fire this off, efficiently answering a creature or artifact