Some remarks:
- Starpriest venom is also usefull on elite units, not just on hordes. For example a stegadon has a potential 19 attacks (without buffs) of which approximatly 2/3ths will hit. So about 15 hits that can proc the poison. That is, on average, only 8 fewer hits than an unbuffed unit of 80 skinks. So on average about 1 mortal wound less. Hordes might be the most effective users, but elite units aren't necesarly that far behind. Plus, elite units are sturdier, making it more likely they'l actually get into combat and use the poison before being reduced to half-strength or worse, annihilated.
- Ripper chief: his command ability affects
all rippers including himself within 18", also
it stacks (one of our few command abilities that still stacks). This will very quickly add up to a lot of attacks as you'l get 2 per model per use. You can build a list around this as well.
- EoTG is basicly a healbot that sits on a stegadon. Which will have definitly have uses in lists with many multi-wound stuffs (heroes, behemoths, kroxigor, rippers, terradons). It makes for a very nice support unit, or a frontline skink to use for vassal as it'l be relativly difficult to kill with all the healing. The limit to one engine per turn is kinda bad though...
Also, for summoning you said you can "avoid" a spellcast, that should be "forgo" or "give up" I guess. Minor detail