Wyvern

Flying combat unit. Attacks land and air units. Decreases the target's armor.

Overview
Wyverns are a deadly force in large numbers. Many missions in the Beast Campaign can be swept through with a pack or two of wyverns. However, it takes time and a lot of gems to train the necessary number of these flying units.

Upgrades
There are 3 consecutive upgrades to increase a wyvern's armor, as well as one major upgrade to increase their attack damage from 22 to 26.

Mechanics
Wyvern's attack reduces the target's armor, and multiple attacks reduce it even more. (This needs to be researched further -- for instance, what is the maximum armor reduction that can be achieved?)

Strategy
Wyverns are powerful and versatile units, so take care not to lose them in combat.

Prioritize ranged enemy units first (crossbowmen, towers, hive spitters, etc) to minimize damage dealt to your wyverns.

High-level wyverns should be revived in Revive Altar, instead of training new ones.

Counters
Lone wyverns can be countered with ranged units or towers.

Wyvern packs are harder to deal with. Area of effect spells should work wonders against them. A counter-pack of Manticore riders will take them out quickly as well.

Campaign
Wyvern becomes first available in mission 6 of the Beast Campaign, "Cold Blooded Kin".