Troop improvement.

There would be an extra tab in the lab where you could upgrade your troops. Unlocked at TH level six. For the unit upgrades which offer more then one attack choice, you could choose the attack type in a new tab next to the unit upgrade tab.

Wizard Upgrades

Inferno Wizard
like the inferno tower it can attack multiple targets or one target doing great damage. Cost- 4,000 DE times the level of the wizard. HP-same. Speed-same. Damage-multiple target-.5 wizards damage single target- wizards damage increasing to 4ish times the wizards damage. Time to upgrade-4 hours times level of wizard. Time the upgrade lasts-(these upgrades are not permanent, otherwise people might feel like they chose the wrong upgrade,) 2 days times wizard level. Looks-level six wizard with beams that look and fire like the inferno towers.

Shock Mage
This mighty wizard has mastered the art of electrickery! His chain lightning is devastating! HP-same. Damage-1.2 times wizards damage. Chain Damage-.75 of damage after each jump. Number Jumps-2 times wizard level. Cost- 40,000 elixer times wizard level
Time the upgrade lasts-2 days times wizard level. Looks-light blue and white robes.

Dragon Upgrades

Frost Drake
Brother of the feared fire drake, the frost drakes breath has the power to freeze buildings! HP-1.1 of dragons hit points. Damage-.9 of dragons damage. Speed-same. Cost-80,000 elixer times dragons level. Ability-the frost drake has a chance to freeze a building for 2.5 seconds times its level. Level one-30% Level two-35% Level three-40% Level 4-45%
Looks-light blue dragon. As level increases color darkens.

I will make more.