whereas magic missile is a "no save and die" spell for many-low level creatures![]()
Hmm, if I translate that into phrasing that makes more sense to me, I think what you're saying is that levitation is not so much problem for low-level creatures (who anyway have low hp and are easily killed), but rather for smallish, high-hp creatures who lack flight or any ranged options. It makes them much easier to defeat than otherwise, particularly in solo fights.Errr... unless I'm greatly mistaken magic missile does hit point damage. ...
Hmm, if I translate that into phrasing that makes more sense to me, I think what you're saying is that levitation is not so much problem for low-level creatures (who anyway have low hp and are easily killed), but rather for smallish, high-hp creatures who lack flight or any ranged options. It makes them much easier to defeat than otherwise, particularly in solo fights.
So can a flying creature change its altitude by flying while under the influence of a levitate cast by somemone else or do they only have horizontal movement?
I would say that if you can fly, you can overcome levitate completely, whether in horizontal or vertical movement. At most, it forces you to spend an action adjusting your position. But that's just a ruling. Strictly speaking, whether it is intuitive or not, the RAW of the spell says, "The target can move only by pushing or pulling against a fixed object or surface within reach (such as a wall or a ceiling), which allows it to move as if it were climbing.", which means you can't fly out of it at all.
I think what you quoted only applies to the caster.Please note that the spell also says "if you are the target you can move up or down as part of your movement" so you levitate me up 20 ft, on my turn I levitate down 20 feet and use my remaining movement to advance on you or move out of spell range which will end the spell. So you never have to worry about being levitated hundreds of feet into the air by this spell if you dont want to be.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.