Mer-Ek Nightblade would be perfect in this deck. It gives everything here deathtouch, and if you want trample Tuskguard Captain

Hardened Scales and Solidarity of Heroes would help with getting more counters onto the field.Ordeal of Nylea for more ramp and counters.

I just realized Mer-Ek Nightblade is already there. lol

lol i just added it to try on playtest cuz of your suggestion :D

U is actually Blue. This deck is BRG, or Jund.

Any deck playing Red in Modern wants Lightning Bolt, because it's just ridiculous. You can afford to cut Ordeals and a Hydra for them, I think. Also, since it looks like you're trying to play midrange-ish (because you're using Kalonian Hydra), you might want to look into Abrupt Decay and Dismember to help you survive for a while, although Decay is a bit expensive.

You are right, i just realized the U lol, ok I will try some changes, thanks :)

Thrill kill assassin nice!