Well, first off it doesn't look like you have a wizard anywhere! (okay, I lie, you have pinkies who are great!)
While you no longer *must* take a wizard to be able to dispel enemy magic, they do help out and it's fun to throw some magic of your own about too! Plus, what makes our wizard's even better is how they buff their basic core unit counter-part.
So perhaps you might want to look at getting a Herald of Tzeentch? He also lets you play about with the 8 basic lores of magic in the rulebook too, so you can have some fun trying out the different lores and seeing what works well for you... (personally, I love combining Life & Metal magic!)
You can get a Tzeentch Herald by droping the seekers for now. (sad I know). But seekers are on the squishy side, and while they're a decent counter to enemy missile troops/war machines, they're about as resilient as an elf against those targets, and with 8th's new rules such as 'Step-up' they'll fold pretty fast in combat...
As for those pinkies, whenever you take a larger unit, I find it key to include the Changeling. His ability to swap stats can really make the difference and stop some big nasty gribbly from trashing your unit!
Sure monstrous units like minotaurs or ogres or elite infantry will still hurt, but enemy characters and lone monsters are no longer any real threat!
You might also want to try your khorne herald on foot as well just to see how he'll help buff those bloodletters. (His mounted version will still rank-up properly in the unit, but you'll lose out on 2 'letters being able to attack due to the herald's huge footprint!)
With 'hatred', those bloodletters will then be able to carve up most anything your opponent puts in front of them!
It's also worthwhile to find the pts to put a Firestorm blade on him too, as there's alot of regen nasties out there. Plus with the Herald striking first @I6, the rest of the unit can then happily hack apart their regen'less targets! (*very* handy against things like trolls, OK units, VC grave guard, hydras, hellpit abombs, etc...)
Hope this kinda helps,