I may be wrong, but AI was less bold in beta 2. Nightmare rook was a real pain in the ass (we were less experienced, though) and displayed a big use of evasion tactics. This is the main point now, they just seem to have lost their sense of danger.
->imput into AI a sens of dangerous things. Not based only of HP threshold, but on HP loss rate as well, as would a decent player do. Of course mitigate this with achieving something : reaching a life potion/dealing last blow to a demigod.
Lower the escaping threshold when key skill cooldowns are not finished. Set it higher when warpstone or other protective item is available and ready.
Add "friendly ground" notion as well. Its defined by presence of large reinforcement or friendly tower. Add support, defined by non retreating allied demigod in vicinity
this would result on the "hazard" test. Of course things can be quadratic or more to express very important values (for instance super low HP levels)
a *HP - b *HP/dt + c * Goal -d * (CD to go) + e * (protection) + f * (friendly ground) + h * (support) < RetreatValue ?
As said, they tend to change target easily, as well as minions and our own demigods as soon as their previous order was cancelled. So to make things clearer
->on player avatars and minions, resume whatever target they were aiming for as soon as an interruption ends.
->when choosing target on their own, tweaks priority list:
for non AOE heavy demigods (beast, regulus, torch without nova, etc)
1 : demigod attacking me/attacked by teammate
2 : melee minions dealing damage to myself
3 : demigod ignoring me
4 : catapultaurii/priest
5 : other minions
6 : angels.
AOE demigods can ignore melee minions and angels. Just make them cast the apocalypse when enough people is at range.
And of course give them objectives. Let them stay against a flag when someone try to cap it, so long as their are not menaced.
Of course help creatures with their pathfinding on some maps, like the dreaded crucible. I don't know what pathfiding technique is used, but putting navigation clues on the maps should be possible.