What a big surprise! After Nekros and Valkyr, our newest Warframe, Oberon, is also quite underpowered and has not much use in a group. For all that he can do there is a better Warframe already.
1. Smite: A power that feels quite cool, damage one enemy and the others around with some projectiles. The only problem with this skill is really that the projectiles do not seem to aim for enemies, just randomly spawn.
2. Hallowed ground: Damage is way too low, 125 is not even enough to put some level 5 grineer down fast. Also the dmaage type is really weak, if we have such a damage type with big drawbacks, I would say let it at least be strong.
3. Dat lame regeneration skill: The projectiles are not fast enough and the healing is a bit weak for the energy cost.
4. A faster version of crush, with worse damage types and less range. Either damage should be increased drastically, due to the bad damage types that have drawbacks against most enemies or range should be higher to make it a good CC like rhino stomp.
In general Oberon feels too weak in damage and healing power, I think one of both should at least be superior, as he is very fragile and not the fastest.
On a side note: The new ember feels awesome, and I find it cool that she has certain damage skills and one to weaken enemies, if this would be the case for more damage types on different frames, this would increase their endgame viability.
The damage lack of warframe abilities in endgame is a great problem for all damage-dealer warframes in the game, I think every ability needs a damage value modifier that scales with enemy level, letting the damage fall off less against higher level enemies.