What abilities does the AI know how to use?

[quartex]

In choosing units for the AI, I was wondering what abilities it knows how to make use of. I know the AI doesn't know how to use healers, and it is very good at backstabbing. I assume it doesn't use nightstalk or ambush at all. What about leadership, does it know to move units next to a leadership unit to gain a bonus? Does it know to move units into a mage of light's halo in order for them to gain a bonus? There's no point in letting the AI recruit a unit with a special ability, if it doesn't know how to use it.

[mpolo]

It doesn't seem to use leadership very effectively, partially because to do so, one would have to split the leader's move, and it presently does a complete move for each unit. Thus, to avoid losing the leader's attack, the unit with leadership usually attacks and only provides the bonus to those who happen along into his vicinity. I'm not sure if the AI gives preference to a hex with leadership when he sends the low level troops in. Light must be similar...

[silene]

it is very good at backstabbing.

In reality, not so good. See below, it is the same as for leadership and lighting.

What about leadership, does it know to move units next to a leadership unit to gain a bonus? Does it know to move units into a mage of light's halo in order for them to gain a bonus?

The AI knows when a combat ability is effective. So it will move a unit near a unit with leadership (if of lower lever), near a unit with lighting (if loyal), behind an enemy unit (if backstabbing). However, it doesn't know how to modify the battle context with these abilities. If a unit needs a damage bonus, it won't purposely move a unit with leadership or lighting near it, nor a friendly unit behind the enemy for backstabbing.
To summarize, the AI doesn't move its units to change the effect areas of abilities, but it moves-and-attacks with its units to benefit from the effect areas. And here I'm only speaking about abilities which have a direct influence on immediate battle resolution. Poison, stone, and so on, do not, and so are ignored by the AI.

[Invisible Philosopher]

There's no point in letting the AI recruit a unit with a special ability, if it doesn't know how to use it.

The AI can use it by accident (especially attack abilities, like poison and stone).
Even if the AI doesn't use it, the unit has combat ability. The unit going into combat near other units makes aura abilities and backstab more likely to be a possibility.