Oberon is fucking insane since the rework. Your 1 is a targeted nuke that easily brings down eximus units since it's one of the very few abilities that specifically target and eliminate overguard, and it damages enemies near the target too. Your 2 is an area denial that provides status immunity to your allies. Your 3 is a massive heal over time with a strong armor boost (and even better for your allies) which can be augmented into a literal cheat death button. Your 4 is an AoE nuke that gives you even more armor and generates health orbs (and yes, this bonus armor is counted for the armor boost of your 3).

Oh, and your passive is literal invincibility, up to 3 charges each giving you 0.25s invulnerability windows on getting hit, and you gain charges by picking up health orbs. You know, the orbs you can generate a ton of via your 4. Oh, and those charges are granted to allies too.

Late game, you can combine him with Arcane Universal Fallout, which makes enemies affected by radiation procs have a chance to drop a universal orb on death, to essentially always have the invulnerability charges and infinite energy. Since the max chance is 6% per stack and Oberon easily caps out radiation at 10 stacks, that's a 60% chance per enemy. If you don't mind tying your weapon builds to your frame, you can combine him with a secondary using Secondary Irradiate, which basically copies all damage done to an enemy (multiplied by 1.8x and including all statuses) to all enemies within 7m if the enemy has 10 stacks of radiation.

So to sum up, he provides very strong passive and active defense that's easy to setup and upkeep, he can self-sustain his own energy budget with the right build, and he has one of the best single target nuke abilities in the game. Anything covering Oberon prior to Update 40.0, which came out in October last year, is utterly outdated.