Lieutenant Lech Kril

Lieutenant Lech Kril is the final boss of Ceres, and also makes an appearance on Phobos alongside Captain Vor as a dual boss battle on the planet. He can be found on the mission Exta on Ceres and Iliad on Phobos.

On Ceres, after defeating him and finishing the mission, you receive a Frost Helmet, Chassis or Systems blueprint. Upon death, Lieutenant Lech Kril has a chance of dropping an Orokin Cell.

On Phobos, he rewards Miter parts and its blueprint, or the Twin Gremlins blueprint. He also drops blueprints for Trinity components. He has two phases, first being Ice and the second Fire, which he will enter after his cryo pack is destroyed four times.

Appearances
Lieutenant Lech Kril wears a unique set of body armor and wields the Gorgon and Brokk. This boss fight comes in two phases, with different abilities and attacks for each phase.

Taunts
Lieutenant Lech Kril, like other bosses, has unique taunts. Here is a list of them:
 * And I will strike down upon (player name) with great vengeance and furious anger!
 * Hold still and I'll make this quick.
 * Trust me when I say you won't feel a thing.
 * Beneath those suits exist flesh. Flesh bleeds. (player name) bleeds.
 * I forgot my nails... I guess (player name) will have to do!
 * Grineer immortality begins with the strike of my hammer!
 * Does that second-skin peel away just as easy as the first?
 * I am Lieutenant Lech Kril. My hammer awaits your skull.
 * I have seen and conquered many clans. (Clan name) will be next!
 * You ever get hammered in that suit?
 * The sound of hammer shattering ice is pure auditory perfection.

General
Lieutenant Lech Kril's battle is split into two phases, the latter phase starts after his coolant pack has been completely destroyed. He generally wields a Gorgon and a Brokk hammer.

Phase 1
Kril is completely invincible. He will generally use his Gorgon throughout the first battles on ranged targets, though occasionally he will shoot Freeze at it. He will resort to his Brokk to knock a target away when they get too close. Alternatively, he will slam the ground with his hammer, casting Ice Wave. Both abilities guarantees a proc.

Kril prefers to stay his ground and tank all firepower instead (though it limits his mobility), unlike most Grineer personnel. He is only vulnerable to damage when all four coolant tube on his cooling pack (on his back) are destroyed, which will then shift the battle to Phase 2.

Phase 2
Lieutenant Lech Kril will burst in to fire and put away his Gorgon and equip his Brokk hammer, resorting to full-melee while turning all of his based ability into a heavy  damage. Alternatively, he may slam down Fire Wave which guarantees proc or throw his hammer at long range targets as a heavy boomerang.

Despite still possessing heavy armor, his melee capability and speed increases by a great margin. He can even catch up to a Tenno and his swing speed is noticably faster. One must be careful as a single strike from him has the lethal potency and can down an inexperienced Tenno.

In General
In Phase 1, Kril's heavy armoring is invulnerable to damage, conserve your ammo and destroy his coolant pack instead. It can be easily be done by flanking him as a team. Solo players can bait him into using Ice Wave and then running behind him to shoot while he's lifting his hammer back up. Alternatively, players can bait him into swinging his Brokk, and shoot him as he's turning back around.

Once the cryo pack is destroyed, you'll have to bait him into using Freeze or Ice Wave again to make him freeze himself. While waiting for him to use Ice Wave, you should hide behind cover or run around to dodge his bullets. Once he uses Ice Wave again, the cryo pack will malfunction and freeze him temporarily, giving a break time (Note that Lech Kril is still invincible to damage even when frozen).

It is recommended to always stay close to cover during this phase. Although his Freeze Dart can be dodged by keeping an eye on Kril's motion, being close to cover can save you if you do accidentally get hit by a Dart and become frozen. Being caught out in the open while frozen can result in getting heavily damaged or killed by Kril's Gorgon.

In Phase 2, while he only can be taken down by mostly kiting, most of his attack is predictable. His Brokk will glow brightly when thrown, note that Kril is stationary while throwing the hammer and until it returns, use this opportunity to damage him. his Fire Wave will be telegraphed by Kril lifting his hammer before slamming it to the ground.

If Kril charges at you and he's faster than you, do not keep running away. Instead, run towards him and flank besides or over him. This will make him try to swing his hammer down on you, thus temporarily stopping his movements, while getting away from his attack.

Utilizing Warframe Abilities
Ash's Smoke Screen, Loki's Invisibility or Shade's Ghost will cloak the player, creating a big opportunity for you to destroy his cryo pack.

Loki's Decoy and Saryn's Molt are also invaluable for distracting Lech Kril's gunfire while exposing him to attacks from the Tenno.

Trivia

 * Lieutenant Lech Kril is a revered war hero among the Grineer. While his assassination will result in stability in the planetary system and intimidate the rest of the Grineer, Lotus dislikes the fact that it will also make him a martyr to his people.
 * He looked like a larger Grineer Butcher before Update 7, and wielded a Fragor instead.
 * Currently, there is a chance that a glitch could happen after one or more of its cooling tubes has been severed, causing the battle against him to stuck on Phase 1, on which the Cryo pack cannot be damaged further. The only known cause is if a someone uses the Rhino warframe while fighting him, especially if Rhino's stomp ability is used.
 * Kril appears in the Warframe Open Beta trailer, though still wielding the Manticore, rather than the current Brokk.
 * He was the first boss to undergo a major revamp, receiving a more complex boss battle and unique voice-acting and animations.
 * Prior to Update 7.5, he used the Manticore instead of the Brokk.
 * He also was the first boss to have a special death animation. Prior to Update 8, on death, he would fall flat on the ground like a downed player before actually dying. It took a little time for him to bleed out on his own, but one could finish him to shorten the time. After Update 8, he now has a new death animation where he falls to his knees and collapses before erupting in a fiery explosion.
 * Lieutenant Lech Kril's taunt "And I will strike down upon (player name) with great vengeance and furious anger!" Is a reference to a scene in Pulp Fiction, in which Samuel L. Jackson states the same as a quote from the Bible's book Ezekiel 25:17.(Not actually in the Bible, created specifically for the movie.)
 * As of Update 11, his shields can be damaged during Phase 1. Although he is still invulnerable, bleeding effect from Slash-based weapons will directly damage his health.
 * His ranking is speculated that he recently came into the Grineer military in a short period before revered as a war hero, as Lieutenant is commonly depicted to be a lower class of command in terms of Ground military forces and Aerial military forces.