LogFAQs > #982002251

Warlock is probably my 3rd favorite class behind Bard and Druid. Ive yet to do a pure Warlock (the one time I tried on an Origin Laezel Honor mode run, I ended up switching to a 6/6 Vengeance Paladin/Lore Bard in act 3 to make better use of a certain broken ring), but 2, 3, and 5 levels of it to be excellent break points for multiclassing.

2 gives you Invocations, namely Devils Sight (Makes you immune to the blind effect from the Fog and Darkness spell) and Appealing Blast (gives a good damage boost to Eldritch Blast), though theres other goodies to that Im sure could be useful in certain scenarios.

3 is mainly for getting Pact of Blade to combo with a martial class just so you can use Charisma as an attacking stat on weapon attacks.

5 is when it gets its best features imo (although 1 doesnt work in Honor Mode). They get one of the best spells in the game in Hunger of Hadar (basically Darkness that slows and damages anyone that starts or ends their turn in it), in which theyre the only class that has access to it other than Bards through their Magical Secrets class feature. And on Tactician mode and below, the extra attack that Blade Warlocks get at 5 stacks with the extra attacks that other martial classes get (which is the only one that does so), so you can get 3 attacks per turn for something like a Paladin (this doesnt work in Honor Mode though).

Next playthrough I do, Im considering going back to try to use a Pure Warlock Laezel (for the medium armor profiency) for the whole game.