Justice is a fan-made global mod.

1. As fktifzobr@mail.ru mentioned, the bonuses from Blood Fury are tied to specific units, and if there are foreign units in the Orc army with the "Boiling Blood" ability (in our case, demons), they will not be affected by Blood Fury (no bonuses will be applied).
2. The "Boiling Blood" ability grants three things:
1) Vulnerability to Unholy
2) Vulnerability to Holy
3) Vulnerability to Blood Fury effects on Horde units
3. Cavern Crawlers are summoned only from the corpse of a unit with the "Demon" ability.
4. I assigned the abilities as follows:
1) Tier 3 Elf +Demon
2) Demons + Boiling Blood; - Demon

Added 8 minutes later
Since Cavern Crawlers are summoned only from the corpse of a unit with the "Demon" ability, which now belongs to the Dungeon faction, I decided to give this ability to Night Hags (we all remember some Tier 3 Elves' penchant for making deals with demon lords - Tralsai, Railag, and others), so it is quite logical and lore-friendly to have such an alternate upgrade for the witch. Of course, it could be replaced - perhaps they could summon a Hydra or a Manticore instead