its a party of 8 lvl 3s. please tell me if its too powerful, or not powerful enough.

there are bars on the ceiling that allow it to use its climb speed, and patches of unraveling magic in the chamber, so positioning will be important

I think it will be an odd fight. The giant can probably drop any opponent in one round at level 3. But, if that’s the only enemy, the party will just nova and with 8 of them, probably drop it in one round, even if it does take one down.

You’ll want to give it some legendary actions to break things up. And give the party other targets, like some mooks or something. 

8 PCs are pretty tricky.  When you have 8 attacks from the PCs, you can depending on rolls do a lot of damage in total.  However, being level 3 any individual PC can't absorb much damage from a single hit.  Basically the Party is a glass cannon.  It can do a lot of offense, but is not strong on defense.

To be honest, this is not a TPK, but it very well can kill a few.

So at a +9 to hit, with two attacks, there is a good chance that 44 points against a single character. At 3rd level that is a good or better chance that one PC is dead.  With 168 points, there is a good chance the Boss will be around for another 2-3 rounds.

That is a good chance to kill half the party.

So as a total party size goes, it is not too powerful.  But you will definitely kill 1/4 or 1/3 to 1/2 of a party.  From that POV it is too powerful.

Keep your boss in the background, until the party is a bit more powerful.  Instead have powerful minions keep the party occupied.  By having minions, you can retreat and/or increase the battle instantly and use a few of these battles to better gauge your party strength.  Realize multiple encounters between rests will sap a party of strength.  So plan for that and having minion battles can assist you on evaluating what is too powerful and what is not.

Quote from Xalthu >>

I think it will be an odd fight. The giant can probably drop any opponent in one round at level 3. But, if that’s the only enemy, the party will just nova and with 8 of them, probably drop it in one round, even if it does take one down.

You’ll want to give it some legendary actions to break things up. And give the party other targets, like some mooks or something. 

 legendary actions might be nice. I plan on having it jump around using that leap, and the chamber its in has bars on the ceiling, so it will disengage, jump up, and monkey bar around with that climb speed, so its not just whaling on an immobile enemy

It's a little thing, but the creature's proficiency bonuses are uneven -- which I guess is because you combined a cloud giant and a nothic, or something like that?

I might change the Rotting Gaze to an AoE cone and also give it a recharge, to reflect it having a lot bigger eye than a nothic

Just to make it more thematically consistent, you could also consider using a cyclops sentry as the base instead of a cloud giant, which would also give it a Silvery Barbs-like Reaction

Quote from AntonSirius >>

It's a little thing, but the creature's proficiency bonuses are uneven -- which I guess is because you combined a cloud giant and a nothic, or something like that?

I might change the Rotting Gaze to an AoE cone and also give it a recharge, to reflect it having a lot bigger eye than a nothic

Just to make it more thematically consistent, you could also consider using a cyclops sentry as the base instead of a cloud giant, which would also give it a Silvery Barbs-like Reaction

 i was using the giant ape (cuz i imagine it moving like a gibbon with thos giant arms nothics have)

rotting gaze and weird insight were orignially AoE, but DNDBeyond had a stroke or something and erased all my progress, so i just copy-pasted

i might go the cyclops route, and defiantley redo those eye attacks

new statblock, with the cyclops sentry

i would maybe give it some saving throws? For a nothic-type giant, strength and intelligence perhaps? i like the pockets of magic and bars for mobility, but I think that a CR 7 might be a bit much for level three, even if there are 8 of them. I would suggest knock a little off the attack damage and drop the HP, maybe take it to a CR 6. It seems to me that this is a skirmisher-type monster, so lean a little more into the range (Javelins, Mind Spike type ability, Make the gave no recharge but single target and give it a multiattack option, etc.)