Genshin Impact - Rhodeia Of Loch Oceanid of Qingce Elite Boss
This water boss drops essential materials for ascending your water characters as well as other valuable artifacts and loot. Unlike the cube bosses, the Oceanid essentially morphs pieces of itself to fight your team, and because of this there are variables that are not found in some of the other lower tier bosses. If you get many birds and cranes, range is suggested as they can fly (seen here) and the cranes love to hang out in the water where you can't hit them with melee.
Boars are dangerous for your ranged damage dealers, and never let the crabs or squirrels anywhere near you if possible, as the bubble spray does a ton of damage and the squirrels are incredibly tenacious! During the battle the Oceanid will also occasionally toss down giant water balls with almost an entire platform radius that do immense AOE damage, it is suggested to swap to your shielded character during the explosion just in case.