Hi! This is how I cleared Veil of Darkness Master Trial 3!
Squad:
Lancelot Berserker
Kai Assassin...
Darrion Holy Defender
Hero Substitution:
Kai can be substituted for other heroes with Refresh on Critical aura such as Aladdin Assassin
Friend:
Friend with highest friendship level
Items you might want to bring:
Dragon Fire
Token Of Strength
Cleansing Serum
Major Healing Potion
Void Guard
1/2:
Attack the Dark Elementals first
The aim is to kill all of them before Valerie can cast her Will of the Blood Lord
Once all the Dark Elementals are dead, end turn until Darrion's cooldown is up before killing Valerie
If any hero in the squad has low HP, use the Healing Potions
Before Valerie can cast Inferno Reckoning, move Lancelot one step back so she can only target one hero.
2/2:
If for some reason, you killed the Valerie in 1/2 too quickly, use Cleansing Serum to clear your heroes of stun.
Cast Darrion's spell
Cast Lancelot's Spell
If you feel you are unable to beat Cassandra in 2 turns, use Dragon Fire on Cassandra and Token of Strength on Kai and Lancelot
Use Void Guard on Kai and Lancelot
