Is there a reason you're playing Deathrite Shaman and Odious Trow? I think you should be playing two copies of Deathrite Shaman if you're comfortable playing the Trow as a dedicated Pact target with limited utility. I've never in my life blocked with a Trow and regenerated it, so I doubt that's why he's still got a place in your deck.

I really don't like Empty the Warrens in a deck playing Summoner's Pact, but it might be necessary/not as bad as I think it is.

I'd play Slithermuse over Meditate, if the choice is between those two. Blue mana doesn't come easily in this deck, so if I'm going to put extra resources into casting a blue spell, I would want it to be better than my regular D4s.