Councilor Vay Hek

Councilor Vay Hek is the final boss in the Earth system. He is found at Everest. He has a chance of dropping one of the following on death: Trinity Helmet, Trinity Chassis, Trinity Systems blueprints, as well as Neurodes, and Orokin Cells.ceramic sword

Appearance and abilities
Vay Hek wears dark gray armor and uses a shotgun, resembling a Grineer Trooper in combat.

Offensively, his shotgun is much more powerful than Troopers and can deal over 60 damage per shot at close range as well as having a high fire rate. He can also occasionally throw a grenade inaccurately that can deal potentially very high damage.

Defensively, his personal shield has relatively low capacity but very high recharge rate and very low delay. He also appears smarter than most grunts, and will much more actively switch positions and take cover to avoid being easily hosed with bullets. In addition, Hek's armor is extremely high, which will reduce a lot of damage from non-armor pierce weapons.

In addition, he has the ability to make multiple level 1 duplicates of himself. He also can't be knocked down by heavy weapon ground slams like that of the Fragor.

Strategy
The fight with the Councilor takes place in a massive cavern with several platform areas lining the walls. Make your way around the outer platforms and steamroll the Grineer troops before engaging the Councilor. If your team includes snipers, use this time to set up position. There is little cover on the main platform; only three closely placed crates.

Due to his shield's high recharge speed, a rifle with high fire rate is crucial to removing it quickly.

Vay Hek's armor is incredibly tough. Even a full team can burn through all ammunition long before his armor gives. Though equiping extra ammo boxes helps, a mid-range firefight is tricky: his gun eats through shields rapidly out in the open. To counter this, it is advised to use a Boltor or Bolto, as bolts have innate 100% armour pierce. It may be hard to hit with though since Hek moves around a lot, so it is advised that at least one to two teammates use other rifles like the Gorgon.

Melee is a good strategy instead, as he has no shockwave stomp attack. Draw him out of cover, circle him closely to avoid his shots, and pepper him with charged attacks. Your proximity keeps him from running to cover to recharge his shield, granting snipers a clear shot. Armor-piercing mods for guns and melee weapons are essential if you are not using Boltor, Bolto variations or the Fragor.

Solo Strategy
If you intend to solo Vay Hek, here's a strategy from personal experience.

Equipment: You'll need a level 30 supercharged warframe, level 25+ super-charged Gorgon with at least Rate, Clip and Damage maxed; a level 15+ Fragor, super-charge is optional but recommended, and your best pistol. For artifacts, Rifle Amp or Enemy Radar is suggested. You also may want to bring one or two rifle ammo boxes just in case.

Mods: For your warframe, including upgrades, you'll need a few good shield and health mods. A total of 400+ shields and 400+ health should be enough. Any remaining mod slots in your warframe should be used for melee damage increase mods. For your Gorgon, you must have at least one mod with 50+% increase in maximum ammo. Remaining mod slots should be filled with damage mods, with at least one armor piercing. A Stun Chance mod is optional. For your Fragor, just put your best damage mods into it.

Strategy: Due to Vay Hek's heavy armor, fast regenerating shields and high health, your biggest concern will be running out of ammo for your Gorgon. As such, conserve your Gorgon ammo as much as possible on your way to him, and use your pistol and melee to deal with the regular enemies as much as possible. Once you're in the arena room, pick off any regular enemies before engaging Hek in battle.

At the center platform of the room, you should see 2 black boxes. This will be where the battle takes place. In the early stages of the fight, Hek will most likely toss out one to two decoys of himself, which you can identify because the decoys are level 1 only. Isolate the decoys from Hek, and smash down the decoys with your Fragor. Now the real fight begins.

You should find Hek taking cover behind one of the boxes. Go and hide behind the other box, so that the two of you are separated by the two boxes. Move slightly out of cover so that Hek can see you. This will usually cause him to toss his grenade at you. Hide back behind the box and wait for your shields to recharge after the explosion, which should deal around 100 damage. Now check Hek's position, run out of cover towards him and do a slide attack with your Fragor. If your damage mods were good enough, this should take out around half of his shields or more. Immediately turn around and start hosing him with your Gorgon while backing away slowly, and remember to aim for the head. After a bit, one of two things will happen. Either your shields drop below 100, in which case you should retreat to the nearest cover immediately. You might take a hit to health, but that's fine. Or, Vay Hek will be the one who retreats to cover, in which case stand there and keep shooting until he disappears behind cover, but don't follow unless he is close to death. Retreat to cover yourself to regenerate your shields, and start the process over until he dies eventually.

When Hek's shields are down, depending on your warframe, you should use the following skills: Ash-Shuriken, Ember-Fireball, Excalibur-Radial Blind, Frost-Ice Wave, Mag-Bullet Attractor, Rhino-Iron Skin, Trinity-Link, Volt-Shock. Don't be afraid to use your abilities as much as possible, as long as each use reaches its maximum potential effectiveness. Also, don't reload your Gorgon unless you have less than 20 ammo left in your clip. This is because if you die, you get 50 energy back (as long as you had no energy remaining before death) and your clip is refilled, potentially giving you over 200 bonus ammo if your clip was low.

Trivia

 * Vay Hek was the toughest Grineer boss before Update 6, which introduced Lieutenant Lech Kril.
 * Vay Hek was targeted for assassination by Lotus as he is a corrupt diplomat who has assassinated multiple political opponents and is a hindrance to the stability of the system.
 * His shotgun is, fittingly, the Hek.
 * He is also one of the more humorous bosses in the game, with taunts such as "Grineer foreign policy starts and ends at the tips of my plasma grenade!" and "Can't we all just get along? Come give your Uncle Hek a hug!".
 * It seems that while Vay Hek's armor color was changed, his decoys were not updated, meaning that his decoys are now yellow while he himself is dark gray, making the decoys even easier to identify.