Blue
Ravenous Bugblatter Beast of Traal
Unlike some previous editions, multiclassing isn't a path to power. Much of your adventuring career the build you put forth will be weaker than a single classed character of equal level. You did avoid one of the big pitfalls of delaying ASIs/feats, but you are missing the level 5 power bump. Also with so many early feats your attack ability scores will fall behind what is the normal.
Frankly, I don't want your first experience with 5e to end up with you getting a wrong impression and not having fun playing a character that doesn't come together until later and your first months you'll be behind the curve. You may want to consider a single classed character simply to keep up unless you are really married to your concept.
- Remember divine smite adds to melee weapon attacks only, not EB.
- Warlock slots are not per encounter, they are per rest. A short rest in 5e is 1 hour, and in a 6-8 encounter adventuring day you can expect to get 2 of them.
- At character level 5 most melee users have doubled their damage output with extra attack. This doesn't seem to be on your plan at any point in the 1-8.
- Some clarification from Sage Advice - the opportunity attacks from Polearm Master need to be with the polearm, you can't use warcaster to substitute in EB. Not that this is definite but just so you know.
Frankly, I don't want your first experience with 5e to end up with you getting a wrong impression and not having fun playing a character that doesn't come together until later and your first months you'll be behind the curve. You may want to consider a single classed character simply to keep up unless you are really married to your concept.