Blue
Ravenous Bugblatter Beast of Traal
EKs aren't strong blasters
Reading these is like "Which subclass of monk should I go for in order to be a heavy armored tank with a polearm?" Sure you can build it, but there are other classes if you want that to be your focus.
There is no "good blasting" except Warlock with optimized EB. In general, single target damage is something handled better with weapons than with spells - which you already are good at. There are good area of effect damage for when you are fighting a lot of opponents (though there's better crowd control spells), but that doesn't get to equally as good as your melee when a large chunk of your levels are advancing casting at 1/3 and you're going further MAD to get up your caster ability for save DCs or spell attack rolls.
If you want to "blast" AND be capable in melee, go for bladesinger, some warlocks, or maybe one of the blasting clerics. The EK is a good subclass, but on-level spells aren't what it's built for.
Building on the fighter chassis with buffs and defenses, and filling in gaps with utility, those are things the EK does well - nay, does excellently. Keep a fireball for when 16 gnolls ambush you, sure. But when you want 50/50 equal time for "good blasting" on a framework that is 100% fighter + 33% limited caster, you're starting with the wrong class to have that balance. You can multiclass, but you'll be behind on both fighter and caster, and even further behind in the spell levels known to fill those spell slots.
What I'm trying to say is if you want to celebrate what the EK excels at you can have a strong build. But if you want that much blasting a full caster build that can also melee (though only at the "50% of the time" level) may be a better fit to realize those goals.
Lastly, if you wanted to be a pretty 50/50 combination of capable melee DPR along with good blasting and some control/utility, would EK 20 or EK 11/Wiz 9 be better?
So for the closest to a 50/50 mix, it would be EK 11/Wiz 9, for optimized blasting while still having good melee capability?
Reading these is like "Which subclass of monk should I go for in order to be a heavy armored tank with a polearm?" Sure you can build it, but there are other classes if you want that to be your focus.
There is no "good blasting" except Warlock with optimized EB. In general, single target damage is something handled better with weapons than with spells - which you already are good at. There are good area of effect damage for when you are fighting a lot of opponents (though there's better crowd control spells), but that doesn't get to equally as good as your melee when a large chunk of your levels are advancing casting at 1/3 and you're going further MAD to get up your caster ability for save DCs or spell attack rolls.
If you want to "blast" AND be capable in melee, go for bladesinger, some warlocks, or maybe one of the blasting clerics. The EK is a good subclass, but on-level spells aren't what it's built for.
Building on the fighter chassis with buffs and defenses, and filling in gaps with utility, those are things the EK does well - nay, does excellently. Keep a fireball for when 16 gnolls ambush you, sure. But when you want 50/50 equal time for "good blasting" on a framework that is 100% fighter + 33% limited caster, you're starting with the wrong class to have that balance. You can multiclass, but you'll be behind on both fighter and caster, and even further behind in the spell levels known to fill those spell slots.
What I'm trying to say is if you want to celebrate what the EK excels at you can have a strong build. But if you want that much blasting a full caster build that can also melee (though only at the "50% of the time" level) may be a better fit to realize those goals.