bedir than
Full Moon Storyteller
Since it's not a Warlock Spell, this build (not a character, because nothing about this contains a story) requires a 17th level Druid to either multi-class or use a non-core feat to grab Eldritch Blast, plus multi-class or use a non-core feat to get Quicken and to use a Feat to get Spell Sniper or it requires, to have a chance to win a single encounter, the use of the two highest level spell slots that the build only would ever get two of (plus the previous multiclass or feats).On round 1 the caster uses quicken, dealing half damage. Round 2 combat is over.
or get ally with arcane eye/familiar to scout so you know when to pre-cast it.
someone with, alert + Haste to give you an extra attack -> Valor Bard -> Eldritch Blast for 12 shots.
And a monk to move you / enemies into position.
And you could probably kill eveyone on round 1.
Spell Sniper solves disadvantage. And will be quite useful for Eldritch Blast/ scorching ray anyways. If the enemy doesn't come close you'll even easier.
Though, using Foresight for your 9th level slot and CME at level 8 is likely more damage.
The "problem" with CME is whiteboarding, not table play.