Ukko

The Thunder Mage (in-game name Ukko) is a lethal enemy typically encountered in either the Snowy Depths or the The Vault, but may appear in other Biomes as well. A telltale electric crackling sound can be heard when they are nearby.

Behaviour
Thunder mages hover about slowly, sometimes dropping to the ground to walk around or jumping to a nearby surface. Their only attack is the Thunder Charge spell, which it telegraphs by briefly charging up the spell, accompanied by an audio cue.

If they are in or near liquid or metal, the material will become electrified, much like the Electricity perk. Additionally, they cannot be harmed from suffocation or drowning.

Be very cautious fighting them around conductive materials, especially water, as they can heal themselves if they happen to hit themselves with the electric currents they cause. Similarly, they will heal from any other sources of electrical damage, so avoid using spells like Lightning Bolt or Ball Lightning when possible.

While the Thunderstone is held by the player, any nearby thunder mages will become friendly.

Combat Tips

 * Thunder Charge is deceptively fast and powerful, but it takes time to accelerate and is most difficult to dodge at long range. At medium range, it is usually much easier to dodge, but its large size makes it exceedingly difficult to dodge at short range.
 * Keep your distance and stay in open spaces. Avoid backing yourself against a wall, as the explosion can still damage and stun you. When dodging attacks, keep well clear of surfaces behind you.
 * Their attack cooldown is just low enough to fire a second Thunder Charge right before the electric stun from the first would wear off. If struck, escape should be the first priority, before attempting retaliation.
 * They possess no weaknesses to any forms of damage, but do resist explosive damage by 50%. The lack of weaknesses coupled with their relatively high health pool can make them difficult to take down effectively.
 * Thunder mages can't target the player from further than 1/2 a screen away. Because of this, it will normally not target you from off-screen, with the occasional exception of them being just barely in range if they're just above or below the visible screen area.
 * They are not overly aggressive or fast pursuers, and tend not to wander around too much. It is usually possible to avoid them if needed, although a wide berth should generally be given.
 * Be extremely cautious fighting them in enclosed areas in the Mines or The Vault, and use cover to break their line of sight as much as possible.
 * If encountered early on, generally the most powerful weapons available will be explosives. Bombs or Magic Missiles can be effective, although thunder mages often prove difficult to dispatch in a single hit due to their explosion resistance.
 * If you have both Explosion Immunity and Electricity Immunity or Electricity, thunder mages are quite literally harmless.
 * Avoid touching conductive surfaces like metals and liquids while they are nearby, as their electrical aura will very quickly stun you and leave you helpless.
 * While they do resist explosive damage, they aren't completely immune to it, and may kill themselves with the explosive component of their Thunder Charge if it collides with surfaces close by.
 * Since they bleed Diamond powder, it's possible to have them fire a thunder charge and it explode on contact with particles of their blood. Fast-firing wands can cause them to bleed enough material to consistently damage themselves with their attacks.

Soundtrack
Track 14 of Noita Official Soundtrack vol. 2 is titled "Ukko Has Other Plans".

Trivia

 * Ukko is the god of the sky, weather, harvest and thunder in Finnish mythology.