Success! I figured how to fix it.
Unit abilities are defined in CoreAbilities.xml.
There, every ability consists of one or several AbilityBonusOptions (for example, Clarity has several versions that regenerate 1, 2 or 3 mana).
Well, what was wrong was that internal name for AbilityBonusOption for IceBlast is IceBlastAbility, not IceBlast. So changing Ice Lord's SelectedAbilityBonusOption tag to use "IceBlastAbility", instead of "IceBlast" fixes Ice Lords.
Code: xml
<AbilityBonus InternalName="IceBlastAbility">
<AbilityBonusOption InternalName = "IceBlastAbility">
<DisplayName>Ice Blast</DisplayName>
<Description>This unit is able blast an enemy unit with ice, causing them to lose their next turn and take 5 damage.</Description>
<Icon>IceBolt.png</Icon>
<GameModifier InternalName="DrowningStrike">
<ModType>Unit</ModType>
<Attribute>UnlockCombatAbility</Attribute>
<StrVal>IceBlast</StrVal>
</GameModifier>
</AbilityBonusOption>
</AbilityBonus>
By the way, Ice Blast does 5 points of non-defendable damage, has hurricane like effect (teleports unit randomly), and makes it lose it's next turn. Sometimes, NPC hero with similar ability can be found.
Does anyone know if this was addressed in any of the new patches or if Stardock was aware of the problem.
I'm aware of it because of this thread, which I was actually linked to from the bugfix mod thread. No matter how trivial the problem is, if there isn't a thread yet for it, please do make one. Anyone that has been around during our previous games should know that we do read the forums and do fix things that we find on here. Apologies for not getting to fix it sooner, but I did fix this problem today, so it should be in the 1.09 update.
For the curious, what I did to fix it was change the name of that AbilityBonusOption to simply be IceBlast. I did this for a couple reasons:
---For one thing, that is how the majority of the rest of them are set up (ie. AbilityBonus with internal name RainOfStoneAbility, has an AbilityBonusOption with internal name RainOfStone. Same with FlameStrikeAbility/FlameStrike, BlinkAbility/Blink, etc..)
---Secondly, not only does the summoned unit Ice Lord refer to the ability bonus option as "IceBlast", but so does the summoned Titan. There was one NPC referring to it under its current name of "IceBlastAbility", so I just updated him to say "IceBlast".