My inspiration for today...it's a bit weighty, but UD is weighty, so Avian can be weighty, too. :P
Avian
No Distance Penalties
-10% Attack Time
-50% Thief Losses
+6% Maximum Population
Immune to Pitfalls
+50% Dungeon Capacity + Prisoners Taken
-60% Honor Losses to Spells + Ops
Spec Names Are Switched
Cannot Use Stables/War Horses
-10% Income
-6% Building Efficiency
+50% Rune Costs
Maybe -5 to -10% Birth Rates
All the spells it had before.
6/0 Elite - 700 gc (cannot lose Elites on the defensive)
Rationale...
No Distance - They fly. More to the point, this provides an attack time bonus for OOW and before war that is useful for Avians without their needing to log on too much per day.
-10% Attack Time - They fly. Specifically, I reduced the time for this and added different bonuses so that a non-Tactician Avian can attack twice per day in war without using Barracks.
-50% Thief Losses - They fly.
+6% Max Pop - They use trees. Counteracts weaker Elite/no Stables.
Immune to Pitfalls - They fly.
Dungeon Capacity - They're birds of prey - they take food for their young...and then use them to attack the enemy. :P Provides some compensation for weaker Elite/no Stables.
-60% Honor Losses (on spells/ops ONLY) - Avians are honorable creatures, and aren't going to give it away easily (again, compensation for weaker Elite/no Stables).
Spec Names Swapped - This is what Avians used to be before they got removed + reintroduced. Current names make no sense with their roles.
Cannot Use Stables/Horses - They fly.
-10% Income - Avians aren't about running a government, they're new to this (provides compensation against the pop bonus).
-6% BE - Avians build nests, not buildings - they're new to this. Helps to balance out all the other advantages I'm giving them.
+50% Rune Costs - Avians are new to spellcasting, too? :P
Less Birth Rates - In case I gave them too much power.
Spells - duh.
6/0 Elite - Makes the Elite a threat by letting the Avian sit around and attack at will when it is convenient. Combined with fast attack times, this could be tactically very useful. Increased gc cost to compensate.