So, About This Focus Thing...

[Institute-Marksman]

After Steve explained it somewhat in the last Devstream, I got kindof interested.

Focus is a sort-of 'ranking after ranking', right? Specialization after your 'frame reaches level 30. 

This would mean that your warframe specializes on an ability or function it has.

For example, Mag, good with magnetics, would be able to control certain aspects of the level.
I imagine being able to control doors, closing them to prevent enemies from coming through, crushing anyone below them or even pushing the door out of its frame. Throwing things around that normally are just scenery, ragdolling or at least staggering anyone in the way. Can also slide out the Corpus' server storage and ragdoll enemies.

Rhino(gonna go full Hulk on him XD), being a tough frame, would be able to bash through closed doors, and shoving crates across the level.

Ash creates a stationary radial smoke screen or one surrounding an ally sticking with them on the move. Enemies cannot see through it, but allies can. Can also teleport an enemy to oblivion.

Ember makes certain objects in the environment lose chemical balance, making them explode, no matter how ordinary they look. Can melt freeze procs and ice hazards.

Frost creates a packed-ice blockade, serving as cover. Freezes doors, sealing them. Can also extinguish fire procs and fire hazards.

Hydroid becomes a small puddle, and is able to move through the level via sliding across solid surfaces. Can increase pressure in water containers and pipes, exploding them and distracting enemies close to it. 
Frost can instantly freeze the water, trapping enemies close to it.

Loki copies the appearance of a targeted enemy, making them believe he is one of them. Lasts indefinitely, but is interrupted when using a weapon or any other ability, when taking damage, and can only walk and run. Performing other strenuous actions(melee included), wil also interrupt it.

Nova ignites her shields, slowly draining them(lasts for 20 seconds), while permanently blinding any enemy looking at her. Warframes remain unaffected, but see her bright glowing shield.

Oberon sanctifies a door or a specific area, inflicting a heavy bleeding proc when enemies cross the field. Can also heal an ally completely by touching them. Works on NPC's as well.

Saryn lets out all of her spores in a big cloud that seeks and infects enemies as it flies through the level. Creates mushrooms on the floor, emitting toxic spores as enemies cross them.

Trinity steals health from enemies she damages, and stores it for when her allies need it. Makes crates and barrels spew out Health and Energy Orbs.

I'll be updating this and adding Focuses of other Warframes. Lemme know what you think below!

[Retrikaethan]

i think what they want focus to be is something like mods but instead of giving frame specific abilites/bonuses you get like "your feet deal damage/knockback when air sliding into enemies" or "rolling causes incoming damage to reflect" or "sprinting into an enemy knocks them down/aside without slowing you down." stuff like that. buffs which occur/can be used at all times. (note these are just examples of what i think they're going for, bonuses which don't step on the feet of abilities or mods themselves)