XCOM 2

The Archon Ruler, AKA Archon King, is one of three alien rulers encountered in the Alien Hunters DLC. It is arguably the hardest Alien Ruler to defeat.

It will be the third and last alien ruler you encounter if you´ve enabled the mission "Alien Nest" at the beginning of your playthrough. If you have not enabled the mission, the alien ruler encounter order will be random.

Like all other alien rulers, the Archon King performs one action after every action made by XCOM during a special Ruler Reaction phase. Some abilities do not trigger Ruler Reaction, like Lightning Hands or Bladestorm.

At some point, when enough damage has been dealt to it, it will open a portal and attempt to escape (if you kill it as it attempts to escape, you will get the achievement "Not throwing away my shot" if you don´t have it already). If it escapes succesfully you will randomly encounter it in a future mission, but it's health will be the same as last time, it does not regenerate.

It is unlikely you´ll be able to defeat it during your first encounter, however, if you manage to do it, you will get the achievement "Regicide" if you don´t have it already.

Here is the strategy for fighting the Archon King:

It has 4 attacks:
1. Melee attack: gets close to one of your units and hits it with it´s stick.
2. Ranged attack: shoots a beam at one of your units.
3. Devastate: the King goes airborne and designates an area to be bombarded by a barrage of pinions which explode on the next Ruler Reaction. Cannot be cancelled.
4. Icarus Drop: grabs one of your units and flies high into the air with them, on next ruler reaction slams the unit on the ground dealing damage. Can be cancelled by doing any damage to the King.

Has the ability to fly high in the air, getting both a defensive and aim bonus.

General tips:
-Take off its armor ASAP.
-Hit it with effects that do damage over time, like burning or poison. It will take damage in every reaction phase.
-You can counter Ruler Reaction with flashbangs, frost bombs or attacks which can stun. Do this when he is down on the ground instead of in the air, to avoid his defensive bonus.
-When hit with Devastate, prioritise moving units with low health.
-When he flies up in the air try to utilise attacks that deal guaranteed damage.
-Try to fight it when it's alone. If possible kill all other nearby enemies first.
-Do not group your squad too close together, to prevent multiple of them getting hit with the AoE attack.
-Move as little as possible. Try to use all your actions to attack.
-Use free actions as much as you can.
-You can use the button to end your turn manually and get back actions from soldiers who already used their actions.
-Psi Op's Stasis ability will lock the Archon King down for an entire turn.
-If War of the Chosen is installed, the ability Dual Strike, available when two soldiers have a level 3 bond, can be extremely useful.