Some editorial bits...
For completeness, the Death Guard Lord entry should probably specify that they all get the Man Reaper attack as well. Or you could say that "Sorcerer Lords, and only the Sorcerer Lords, have the
Warp Bolt..."
Stubborn - "hackdown" should be in quotes, since it's not a term used in the rules. It states that it refers to hits due to losing "close combat" rather than assault. That's bound to cause confusion. Also, it doesn't state whether it applies to the "wiped out" result of losing an assault while broken. Are those treated as mass hackdown hits, or are Stubborn units still wiped out?
Quote:
All units that are Stubborn may make their normal armour saves (including any re-rolls that may apply) against the automatic hits ("hackdown") caused by losing assault resolution or caused by suffering Blast Markers when broken. [Insert sentence on what happens for a lost assault when broken.] Note that Stubborn units are still destroyed outright if they are within 15cm of enemy at the end of a Withdrawal move.
Your core retinues are 6 units each. Was it intentional to dump the 7-unit count?
I would consider moving both the Terminators and the Plague Zombies to the support formations. You've already restricted the support retinues heavily, so that would replace the need for the 0-2 restriction on those formations.
I would take the Land Raiders out of the Support Vehicles upgrade and just leave them in Transport. The formation restrictions end up the same. You can take up to 3 support vehicles, enough Land Raiders to transport the entire formation, and enough Rhinos to cover anything not carried in LRs. That would let you remove the caveat under the Transport rule.
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And on a side note, I'd really like to see a 10-unit Havoc garrison on OW. First activation, summon meat shield plague bearers, go back on OW and dare anyone to come after you.
"This part of the board is mine! Now we fight over the rest."
. This seems very much a problem that can be shown in a battle report. That formation would be rather expensive, 575 + demons you want to buy. So they should be able to have strong effect.