I put some new ideas in there:
While all Deep Lords can access the common rooms and spells, a Deep Lord that decides to specialize into any of the paths will adquire advantages like unique rooms, bonifications, spells and special creatures. To advance into any of the paths you will need a library and researchers.
THE PATH OF WAR: Brawns over brains, emphasis on large number of melee troops, cheaper creatures costs, many creature support spells but weak damage spells.
Unique rooms:
“Arena”: free training but creatures get injured and near death;attracts ogres and makes orcs become warlords once they pass certain level
“Hell pits”: While creatures are here they will summon weak but mindless hellish drones that rush to attack enemies. Imps promote to firelords (a hibrid warrior-mage), attracts Hellhounds.
THE PATH OF MAGIC: We have a good couple of fireballs, where the War Deep lord would rush towards his enemies, the Magic Deep Lord will rush along the tech tree and adquire superior spells consisting of hexes, curses and high damage spells. Long range casters and their unique creatures like the liches (able to raise skeletons from just slain enemies) turns them into an army of a few elites and lots of cheap cannonfodder, while their spells and increased mana generation will help keeping at bay any early game attack.
Unique rooms:
“Dark temple”: creatures generate mana by praying, Attracts bone golems, Skeletons promotes to Death Knight; once they pass certain level
“Hall of the dead”: sacrificing creatures here creates Abominations, High level Warlocks become Liches, attract nigthmares
THE PATH OF STEALTH Deep Lords going down this path prefer to create impenetrable fortresses out of their dungeons and wreak havoc while confortably sitting in it. Their extreme proficency at cheaply crafting traps and secure doors for their dungeons and unique gold generating room will make assaults really hard on this self sustained keep. Not just that, special creatures able to turn invisible will join them and sneak into enemy keeps to destroy their most important rooms and assesinate sleeping soldiers. They are expert harrasers but have a slow but safe play-style.
Unique rooms:
“Casino”: recover money from your creatures, (Jackpot winner!!)Attracts Cuttroaths, promotes goblins to goblin rogues
“Den of thieves”: while it has workers, slowly drains money from enemy keepers treasury; Attracts Shadowbanes, promotes Imp to “Shadow Lord”
Units may change, but, what do you think of the new rooms?, Den of thieves could be changed to "Sweatshop", where any creature dropped (enemy or owned) does forced labor to win a bit of money over time but cant be recovered and dies after some time. Worshop innate production value can be used here, good working creatures like the blacksmith produces more money than a mage or cultist.
“Hell pits” migth be a good addition, and it fits such an agressive oriented approach, each 3x3 could contain an altar, your minions would need to summon (work) the kamikaze demon drones, only 1 drone per altar allowed, the drone rest in the altar until an enemy is detected and they launch themselves at it. They constantly lose health after leaving the altar so they migth die naturally before reaching long distance enemies; "working" on an already summoned drone makes it win xp/level up so its more effective, also high level creatures can summon stronger drones from the go. No new drone can be summoned until one dies.
Of course more intelligent creatures would summon better, so the innate research value of creatures could be used here, being mages better summoners than an orc or spider.