Is it possible that the ember burst attachment caused the impenetrable nimbus to slip off - so that the next attack went through? Please use the console log when reporting issues like this (F1), as it shows more information regarding attached cards et c.
Yep, it looks like that is what happened. After the Nimbus was attached three other cards were attached - your own firestorm, a cold of some sort, and your own ember burst. The second firestorm would have just replaced the first, so it doesn't count toward the three card limit or in this case change the order of those cards. Since you can only have three cards attached to a character at any one time, after the ember burst the nimbus slipped off!
Yes, this looks like what has happened. I'll try to pick out the relevant bits of the log in chronological order: Patsy makes someone temporarily invulnerable - Umbario has Impenetrable Nimbus attached Galeldirer Earth-changer jolts Umbario with a blast of cold! - Umbario has Frost Jolt, Impenetrable Nimbus attached. Umbario fills the world with roaring flames! - Umbario has Firestorm, Frost Jolt, Impenetrable Nimbus attached. Umbario detonates a ember burst. Impenetrable Nimbus reduced damage to Umbario by 3. - Impenetrable Nimbus negates the damage from Ember Burst. Ember Burst is then attached, discarding Impenetrable Nimbus. Umbario has Ember Burst, Firestorm, Frost Jolt attached. Sharp Cucelden delivers a vicious stab to Umbario Umbario took 4 Piercing damage. Umbario died. Everything looks fine, at least so far as I can tell.
I forgot about the 3 card buff/debuff thx for pointing me at it. @ pengw1n I never knew about F1 till now.
