Best would be CME + Scorching Ray.
But that takes your 2 big spells and does appropriately big damage.
Dunno why that would be unplayable.
Warcaster and Spell Sniper.
Misty step into position.
Attack, nick (at -1), Eldritch blast * 3 = 5 attacks.
Action surge, attack, Eldritch Blast *3 = 4...