Rune Chain Spell not working - after selecting friendly troop
 

The spell will increase its damage if you sacrifice runes from one of your troops - once your troop is selected - however, you cant cast the spell anymore - moreover - if you reselect the spell in the spell book - it will now say it does the 250% damage on the enemy target - but it wont, it will still do the normal damage without enhancement.

Sometimes also, after selecting a friendly troop - the game displays the hourglass for a unspecified amount of time

Nobody ever wanted to use the spell? Its theoretically the highest single damage spell with lowest mana that can be double cast if you ignore pain mirror which requires that the target has done any damage.

You're right, this spell is great for single-stack damage, I had not realized it before (I looked at lvl1 and the damage did not seem impressive to me, but it scales really well with higher levels).
But it worked as it should for me when I just tested it - first select one or more friendly troops to take runes from, then the enemy. And the damage was correct.

Incidentally, I noticed something else: the [edit: morale bonus from] bloody pentagram from demons does not affect summoned demons (from demonologists and demons themselves), even though they are friendly (but fighting on their own).

It does not work for me - when i select my friendly troop e.g. runemages which give me +300% - i cant select an enemy drop enemy - the magic wand still shows but it doesnt highlight enemy units nor does left click do something - and as i said - it then shows the hourglass and nothing happens

this really sucks, because it would do 5000 damage for only 7 mana for me

I just try the rune chain spell and it's very strange, i don't think it's working as intended.
For example, it collects 4 runes from my griffins and it says "damage +200%" (50% per rune), then on the enemy target it says 2700 damage (the spell has a base of 1800 for me).
Next i try with the soothsayers, it collects 5 runes and says "damage +250 %" , then on the enemy it says 9000 damage and effectively did 6300 damage.

edit: ok i just try again and it worked as intended (collects 4runes, +200% damage and did effectively 1800*3 damage). It's erratic! :)

edit2 : it seems to deal the right amount of damage after all, it's just the display above the target ("xxx damage, kills : xxx) that is wrong sometimes.

I think the display gets stuck until you update the "runes consumed" - i.e. after you cast it once (I had damage +250%, 7000 or something) it will only update as soon as you take runes from a unit (at first, it will still show +250% when casting it again). But I do not get the bugs Harakiri described.

The bug occurs due me using the interface mod mod_wn131_interface.kfs which allows viewing higher level spells before upgrade etc - when removing the mentioned addon, the spell works fine.

Too bad, the mod is really useful

maybe it takes out some damage due to the target's magic resistance?
I'm running with dragons and some snakes (for stone skin spell needed to upgrade Guardian Angel medal) and I'm using this spell on snakes, which gives me 3 runes = +164% damage (+55% rune dmg from the spell itself). so, the spell itself gives 1550 dmg and combined with runes - ca. 4700 dmg. so it's working correctly. I have 6245 build (updated to 6246, but too far into the game to restart).

Wish I had read your post earlier, it has been messing up my game and I only now found out why. This file (mod_wn131_interface.kfs) has a lot of .lua files in it that have since been updated. The author would need to keep udating the pack every time a patch comes out to use the most current .lua files embedded in that pack.

And I agree, it was really useful. At least we can save it, ugprade, and load it if we want.

2635 + 325% for me.
The first time i cast the spell, it displays about 30k dmg, but it's fake.. It just counts all the runes, not just 5...
The 2nd time the spell counts the 5 runes correctly and displays something about 12k dmg.