I'm also not wild about the mis-match of havoc weapons. 2 flak missiles/1 AC/1LC per squad is a little funky to work with as far as target priority as all 3 of those weapons generally have different targets. I'd recommend putting the flak ML's together and either go x4 LC or x4 AC not 2/2, that way you're not wasting shots per turn.
What I thought about the havocs, was the following:
1. Be able to threat AV 14s (2x krak, 1x las)
2. Add 2 Autocannon shots, and it's also good anti-transport (no need for 4xAC)
3. After tally hits the top, Frag Missles allow no armour saves. So we got 2 frag missles, plus 2 autocannon shots which allow no armour saves (the lascannon would allow no saves anyway due to AP2). This is respectable amount of anti-infantry firepower as well.
4. The flakk shots are mostly "complementary", in the sense that fliers are not the top priority of a tally list, at least for the first few turns. In synergy, however (ie an enemy flier that HAS to be destroyed), those 2 squads will shoot 4 flakk shots, and 6 autocannon/las shots, making 2.6 flakk hits, and 1 more hit from the autocannons/lascannons, 3-4 hits total.
Even a single unit will score 1.3 flakk hits, and 0.5 auto/las hits, roughly 2 hits, better than nothing.
So, the way they are kitted, they can deal with a variety of ground targets (good vs light vehicles, rudimentary vs fliers & heavy vehicles, good vs infantry after tally hits the top).
If epi doesnt show you're a sitting duck.
Everything in this list is designed to rack up kills, how is that a sitting duck? O.o
That makes it doubly bad for you tho'. Now instead of having to split the effort between gaining objectives and taking down the puss ball your opponent can afford to focus their schwerpunkt on Epidemius and if they take it down (and once you get to him Epidemius ain't that hard to take down), not only have you lost the major investment that puts your guys to a higher plane but you've lost an objective as well.
I replaced Typhus & the cultists with a Sorcerer and a Plaguemarine squad, comments on that please?
PS: I am going to edit the original post with the updated list