Threat and taunts: who the monsters hit

How threat and taunts work in The Ember Depths 0.20: what builds threat, how it fades, when foes switch targets, taunts, Unswayed and dropping threat.

Monsters no longer flip a coin to pick a target. Each foe remembers who has hurt it lately, and goes for whoever matters most to it right now.

Damage builds threat. A tank builds a lot more of it than anyone else; a healer's heals build a little (40% of the healing, shared by the foes nearby).
Threat fades: it halves every 4 seconds, so a fight keeps moving. With no threat at all, a foe goes for whoever is closest.
Switching takes a clear lead. A foe changes target only when someone has well over its current target's threat, and never twice in a blink.
Taunts hold a foe on the tank for 3 seconds (half that on bosses) and leave the tank on top of its list, so it stays. A red crest over the foe shows it, blinking just before it ends.
Unswayed. Taunting the same foe again within 8 seconds holds it for less time, and after the third it shrugs taunts off for 4 seconds (a grey crest).
Defiance: a tank takes less damage from the foes it holds, so holding them is safe.
Dropping threat. Damage dealers have dashes and talents that shed threat (and some hand it to the tank). A foe that slips away from your tank shows an orange "!".
Taunts and interrupts always land, even when the attack roll misses. Sellsword healers let the tank pick up a foe before they hit it.