I'm a stupid-big fan of the Blight Beast Paragon Path, but it's really a what-kind-of-druid are you thing. With the Blight Beast and a focused Beast build, you're easily doing Striker damage right away at paragon and by level 16 it's just ridiculous with every enemy hit getting vulnerability 5 to your next attack. I love playing a melee controller, it's just so freaking weird...but crazy fun.
Thank god this is voting for favorites and not the best. The Blight Beast paragon has the problem of having almost nonsensical "when you spend an action point" text. Seriously, check this out:
Blight Action (11th level): Whenever you spend
an action point to make an attack, all enemies adjacent
to you must move 1 square away from you or
take ongoing necrotic damage equal to your Constitution
modifier (save ends).
I play this character in the RPGA so the DM changes now and then and everyone reads this differently. Do they move immediately? Can you make Opportunity attacks on your own turn? If they move 1 immediately and now you can't attack them, did you waste an action point? Was it meant that they move on their turn?
(By the by talking to customer support, I'm told they move immediately and provoke AoO, even from you, even though it's your turn. Which seems wonky.)
Terrible case for my favorite Paragon path, but the Undead Beast flavor just wins for me.
-Jared
"bringing shame to his favorite by mentioning its flaw"