Saeviomagy
Adventurer
"Marked" reminds me of dog + fire hydrant..but seriously our group is "this" close to removing it from the game. It's a lot of petty tracking IMGO (in my group's opinion).
jh
Removing it from the game will wipe out the 'stickyness' of monsters and defenders. If you're fine with the PCs always going for the squishyest foe, and as a DM having the monsters do the dumb thing (because if THEY go for the squishyest foe, it makes most of the strikers pointless - they'll simply be dropped in the first or second round of combat), then it's ok.