First, what are "G. Horde bases"? I'm assuming you're referring to Nurglings, and if you are, I'll tell you now that they're way more than just speedbumps.
-Lieutenant: Get rid of Plaguesword, add on Manreaper. Much better. Rather than Essence or Mutation take Strength.
-Never take Powerfists in Termies.. always Chainfists, Power Weapons, or Lightning Claws if you've got leftover points with no purpose. I suggest taking your current configuration down to 2 Chainfists and 2 Power Weapons, and you'll save some points.
-The Traitor unit doesn't have to be that big. 10-12 should be more than enough to keep the Missile Launcher alive.
-Take the zombie units down to an even 20 each.
-More Nurglings
Other than that, it looks ok. I'm not at all a fan of Sentinels, but the rest of the list still looks almost like it would work. I'm concerned with your lack of Anti-Tank, and I'd drop the Defiler for some more small (6-8) squads of Traitors with Missile Launchers for more long range support and anti-tank (rather than pinning too many points on a huge, ugly tank that fires in a random fashion and can be destroyed by one hit, which is attracts since people tend to be afraid of them).