This bug report wants a word
Kraken is specifically designed to work differently, because the spell specifically says damage, then create gems, and LASTLY devour.
Further down that “bug” thread the devs decided that the damage should be converted to a devour if that chance resolves.
“Deal [Magic + 4] damage to an enemy, with a chance to Devour them equal to my Attack.”
Your question about Invulnerable troops got me thinking so I ran some tests using fully traited Dooms.
Medals and the event have nothing to do with it. Mana Burn works against Invulnerable troops as it is coded. Now I agree that if Impervious is immune to Mana Burn, Invulernable should be too and should be looked into.
I crashed a fully traited Psion into the Dooms a few times from skull attacks as well use his abilities. In all cases the Dooms did not lose their mana nor did Psion gain any from a skull attack. So preventing Mana Drain is functioning properly.
So if the intention was to always allow Mana Burn to work vs Invulnerable troops then it is working as intended. But if Invulnerable was supposed to stop Mana Burn, definitely a bug.
Not according to the text.
It just says it’s Immune to Mana Drain.
Mana steal is a different mechanic than drain.
As dictated by the explanation for Mana Shields.
I agree that at the least, the card text should be updated for better clarity.