Also, dear
Desiderius, there are capstones - and there are milestones. They require meta-knowledge, but it is widely available now.
If dips make the performance of the character be subpar at some important events - like the Gray Garrison, the siege of Dresen, Playful Darkness and so on - then the multiclassing is bad or, at least, badly timed. However, if dipped characters
peak at exactly those moments - then multiclassing is good.
And going for mods with Owlcat's awful QA is just a bad taste. It's like not washing for several weeks; one can have sound and legitimate reasons for that, but s/he still stinks.
I'm thinking of going Lich MP, so Death Knight, of course.
See, this is how the language interferes with perspective.
In English "death" is masculine, while almost all of the nouns do not have gender. So the word "death" stands out, and it is a "he". So powerful Death Knights on horses and so on come to mind for you.
In Russian
every noun has a gender. Every one of them, you cannot speak proper Russian without gendering everything. And death - "смерть" - is feminine. Usually she is depicted as the crone with a scythe who just reaps souls without much effort. Like grass. Or, in some modern cases, not a crone, but a girl, sometimes not even ugly.
So I am planning my Lich as a female Dhampir Cruoromancer, extremely fragile, maybe with 8 in both CON and STR, but very intelligent, beautiful and graceful. And deadly. With as much focus on necro DC as I can muster. I think even a suboptimal wizard is good enough for Hard.