Age of Wonders III - AoW3 Wiki

Arch Druid: Good synergy between Shamans having Entangling Touch and Hunters having Coup de Grace and Throw Blades, especially considering Shamans get Were Bear making it alot more feasible to have them in melee. The damage they can rack up between Predator and Bloodthirsty means they can be very adept at blocking for your hunters and mystics.

Dreadnaught: Kinda Specific Synergies like Sabotage on the Sphinx, and Sprint on the Engineer. All in all not bad at all, when its useful its very useful. But most of the time your probably not fighting other machines or trying to breach walls with flyers. The sprint on the engineer obviously is useful if he got engaged in melee, then again most units that can engage a Engineer that doesnt want to be engaged are either flyers or Strong units shrugging off a couple of Opportunity attacks to get to him(Archon Titan, im looking at you). Either way they probably will oneshot him. Still nice at the start.

Necromancer: Some slight buffs for the Death Bringer in the form of Predator and Athletics. Also their Spirit and Fire Resistance nicely counters their Undead weaknesses while being undead solves their inherent Frost weakness. The Ghoul Sun Guard especially stands out as a very good Tier 1 unit that punches well above its class with Life Steal, 80% Fire Resist(with Embalmers Guild) and 62 HP for a Pikeman unit. They also bring Fire and Spirit damage to the Table via their Racial support unit, something that helps especially against other Necromancers and clearing early undead camps around your cities.

Rogue: Only Tier 3 Racial Irregular, which gets a nice Buff via empire updates in the form of Backstab and an extra Iron Medal Text Rank making them quite nasty customers considering they are Tactical flyers and can flank with impunity. Their Assassins gain the great Pounce instead of the redundant Pass Wall at Gold Medal Text Rank, they also get Improved Wall Climbing which makes getting up on walls with your Assassins a little bit less suicidal(Also a good perch to pounce from).

Sorcerer: There is little Synergy, the Apprentice even gets a slightly upgraded Mystic Attack doing Spirit and Fire Damage. Considering Mystics start with Projectile Resistance (which Sorceror Supports get via a in this case redundant Empire upgrade) and Break Control while having Were Panther its all a bit conflicting without offering significant extra options.

Theocrat: Not much synergy to be honest, in fact there is some conflict like the Transform ability on their Support removing the Empire Upgrade heal ability or their extra Spirit resist being wasted on Strong will Class units. Nothing really bad, but nothing really good either. The highlight is pretty much the Sun Shield on the Crusader, which does significantly increase survivability against Fire wielding enemies.

Warlord: Very high fire and spirit Resistance on the Phalanx due to a mix of Sun Shield and Racial resistances. Predator in conjunction with Athletics helps the Phalanx block paths and makes opportunity attacks from them that much worse. Their Manticores and Berserkers stand out via their Pounce ability, which is similar to Defensive Strike, only that it teleports behind the target to flank it, can be used every 2 turns and does 3 extra damage.