CapnZapp
Legend
Cloud of Daggers + Hold Person: First I thought "oh ye olde deny Dex saves trick", but this is simpler - it's a Hold Person you take damage from.
Since Hold Person in 5E is much more a spell that enables your party to damage/kill a creature than its traditional role of cc (taking a dangerous monster out of the fight to be dealt with later), this isn't actually too unbalancing (since all it does is slightly accelerate the process of removing all hp from the target).
Suggested spell level 2+3=5. Actually, I'm not sure this will see much use as a level 5 spell. (At least this means it's probably not overpowered)
Charm + Fear: Not sure I see the point. What does the charmed condition add to someone already affected by Fear? I could see a combo of charmed + frightened, so you're warded not only from melee brutes... but the Fear spell forces you to spend your actions on Dashing away, which is much more relevant than any of either condition.
Suggested spell level: 2 (persons only obvs). That is, as a whole new spell that targets a cone of people with charmed + frightened but no running away.
Bless + Curse: I'm assuming you mean Bless + Bane... This would be a pure action economy win... and Bless is already a popular spell, so:
Suggested spell level: 1+1= ...3 (too good at level 2; probably not good enough at level 3, so level 3 it has to be)
Enlarge + Finger of Death: Does this mean the target is raised as a large Skeleton if the damage kills it? Or does it mean it actually heals AND enlarges a skeletal undead? Or maybe it means a skeleton is enlarged and then points at a foe to cast this spell? I can't find any synergy here...
Polymorph + Dominate Beast: I like it - polymorph the foe into a beast so Dominate Beast works on it!
Main problem, either it's overpowered or underpowered. Restrict it to persons and you could simply use Dominate Person (at the next level higher). Don't restrict it, and the spell must be raised three levels or overshadow Dominate Monster...
Other than that polymorph doesn't add much that dominate doesn't already give (except extra hit points!).
I can see this as a variant spell for Druids. (Make it level 5 and restrict it to persons. Essentially all it does is add an in-game explanation why druids can now dominate persons)
Fog Cloud + Storm sphere: Hmm. This only adds heavy concealment and size upcasting. Not sure I'd cast this assuming one level higher (5th), even if I could then cast it as a 6th level 40 ft sphere.
Probably the most interesting variant would be to envision what a level 2 or 3 cloud could provide: maybe the (modest) bludgeoning damage and hearing disadvantage at level 2; maybe the lightning strikes at level 3.
