swift kraken
Character is an elf, finished all of Blaanid's Boost Missions so I'd have some skill versatility. I solo'd Cromm with Final Shot, but my arrows aren't even denting Crumena's health.
I tried googling tips and seeing what he may be weak to, but the only video examples were made 10 years ago lol Should I still be focused on ranged attacks and skills? And how much damage would be enough to knock him to the ground before he summons projectiles? Any help is appreciated.
crisp cosmos
you can use meteor strike to kill it
else you can hit and run with archery mounting
cedar trail
Crumena is a very big challenge to solo for an early-game player. He was implemented when "raid bosses" became a true challenge that required multiple people to subdue. He has ~50,000 health and resistances to all damage types.
Some general gameplay mechanic tips:
Crumena's body parts can be damaged individually, causing various changes to his behaviour. We're not entirely sure what, as it's always been hearsay.
Crumena's "Roar" will de-summon your pet. Focus on debuffing Crumena quickly with pets such as Bone Dragon and Mir, and then use self-reviving pets such as Nimbus and Scooter Imp to distract him so you can focus more on damage. (They will not survive for long.)
When Crumena roars, attack his chest. His resistance to damage is temporarily lowered. (This attack will desummon your pet.)
When Crumena roars skyward and the sky turns gloomy, attempt to windmill between his legs before he can take-off. This will sometimes cancel his flight. If he successfully takes off, use the skill Lightning Shield to defend against his "Rain of Thunder" skill. This skill cannot be dodged and deals huge damage even if you block it. Use Mana Shield to buffer your health during this skill.
If Crumena flies up without roaring first, he is using "Meteor." It's advised you run away from this attack, as it's a matter of luck if you avoid getting hit.
Keep an eye out for Crumena's "Fire Breath" skill. It will kill you. Avoid standing infront of Crumena.
Generally speaking, standing just behind his legs is a safe(ish) area. It also puts you in a good position to use windmill. (But use it only when necessary.)
Lullaby works on Crumena, use it for a long opening to ensure a skill with a long cooldown like Meteor doesn't miss.
Memory/Divine Link useage is limited due to Crumena's ability to desummon pets. You may find your pets serve a greater purpose as a distraction rather than mobility, even as an elf.
If all else fails, find a party!
Lightning Shield works better when multiple players overlap it, and there will be more openings to attack with more players to distract Crumena.
Alternatively, as Tato has mentioned a stronger player can kill Crumena in one hit. Even at your level, a high rank meteor strike should be enough to put Crumena at half HP.
Hope that helps, and good luck on your Solo attempts.
crisp cosmos
If you do run away from Crumena when he's flying. Go to a bridge nearby to avoid his attacks
swift kraken
Thank you both sm, gonna re-attempt the boss after work tonight. 
If I fail again though, I'll try getting a party together.
crisp cosmos
feel free to ask