Hi,
The builds I was tinkering with where Eldritch Knight/Bladesinger (aiming at 10/10) and Arcane Trickster/Bladesinger (aiming at 12/8).
Since we're in an optimization thread (weird that this thread is here rather than in the optimization forum), I feel comfortable pointing out that you might do better aiming at a different class split.
EK10/BS10 is a very unfortunate split. EK11 grants an extra attack, so if you're going for 10, why stop there? BS11 grants a 6th level spell; Mass Suggestion is a favorite, but you can fill your spellbook with choices since you're a wizard. I'm not convinced that EK/BS is a good multiclass to begin with, what with the redundant second attack and other issues, but 10/10 is a particularly unfortunate way to go about it.
Rogue/BS is more interesting, yet I'm not sure AT serves as well as, say, Assassin, along the lines of Assassin3/BS17, providing Improved Invisibility, 2d6 sneak attack, 2 attack/turn and a reasonably fun surprise round at character level 10.
OTOH, AT14/BS6 does provide 2 attacks. Though AT13/BS7 also provides Improved Invisibility.
Note that blast spells are *even worse* for multiclass characters of this kind, because you get them later. An 8d6 Fireball that was worth considering at character level 5 is a great waste at character level 10.
Leaving that aside, both characters you are considering are gishes. They have damage covered! Presumably, you plan to put out pain with weapons. Despite this being a God Wizard thread, with associated flavorful snark about lesser characters, dealing smackdown is part of a complete breakfast. Diluting Rogue or Fighter with BS should a) not impose dead levels and b) enhance the main thrust of your character rather than diluting it.
Because if you really want to damage stuff with Fireball, the only correct Wizard build for your first 5 character levels is Wizard 5, pick your favorite subclass. Fireball is a fine spell to spam at level 5. Increasingly less fine with every character level that passes, regardless of what slot you use.
But if you want a relatively even class split, you need to choose spells that enhance what you want to do, which is *not* be a primary spellcaster.
Both will have higher spell slots and only wizard spells. The usual scenario is 3rd or 4th level spells and 5th or 6th level slots for levels 10-15 (+1 to all if you reach really high levels).
I do see your point. What are good alternatives then? What do you think are the least bad scaling wizard spells in slots 5-8?
Animate Dead seems to scale well. Hold person is situational. Banishment should be decent too. Are there any more?
I think there are two good guides that cover this... one of them at the beginning of this very thread!
(Of course, unless you're playing to level 20, chances are you'll never see the spell slot anyway.)
Anyway,
Ken