There are not only synergies in multiclass builds, but also in builds that do not work together as multiclass, but should be two seperate characters.
Notably, aura of dread from Oathbreaker Paladin lets Necromancers add the Paladins cha to all attacks from their minions. Which are A LOT of attacks. So this is quite strong!
Also, bard + warlock/ battlemaster is good, since they rely so strongly on short rests
