I need one more kagrumez gem and i heard he sells one. But hes nowhere to be found. Can he be killed? It may have been a dragon.

He is just outside of Tel Mirthyn or however you spell it - Neloth's mushroom house/tower. Follow the sounds and you can't miss him. He does indeed sell one of the gems. I am uncertain if he can die. I believe he can but i'm not 100% so don't quote me there.

thats what i feared. I know where his tent is but hes not there like he was at one point ;_;

He can die.
However, there are five gems on Solstheim and you only need four.
Two can be found in Kagrumez, two at the end of two other Dwemer ruins and one at the Silt Rider merchant.

Does anyone happen to know where the one in the aqueduct place is? I already went through that quest ;_;

For both of the Dwemer ruin ones, theyll be at the end of the dungeon by the boss chest.

Locations:

x2 = Kagrumez (Can loot from Reaver in main arena area)
x1 = Silt Strider Merchant (NW fo Telvanni Tower)
X1 = Falbtharz (On Dwemer plate next to the Steam shooting Dwemer Mask)
x1 = Nchardack (In room off of steam pump area to the right. If you hang right once you enter the room after dropping the bridges, the area is to the leff of the activation pedestal)

Reward after going through the Arena tests, Dwarven Black Bow of Fate. A black Dwemer bow enchanted with he Chaos enchantment. Ridiculously awesome for sneak archers.

.....such a freaking awesome quest....

I found this post on another thread that details the locations of the resonance gems.
Hope it helps