Here is the full list of all 25 Royal Heroes achievements.
Discover all air spells
Discover all void spells
Veni Vidi Vici!
Discover all earth spells
Discover all water spells
Discover all fire spells
Hire a 4 star hero
You can't be a winner all the time
Do something useful. DOIT!
Flawless victory - no casualties
Dont be a Batman - do it!
Warp a few times
Find and restore a famous weapon. Get Warping Power increase.
Find and 'pet' at least 10 sheep
Clear a whole other dimension. Get Warping Power increase.
Sacrifice a weak one to make your army stronger
Collect the whole set
Craft a weapon that only the worthy can wield
Come to dark side. We have cookies. And extra spell slot.
Find and kill all of famous vampires