StarClan's Anger, known to us as PWNAGE, was when StarClan got mad and PWNED the kitties. They sometimes cover up the moon or hit kitties with lightning when they're ticked off.
Angry Ancestor

The StarClan kitty is mad.

The cat that ticked off StarClanEdit

Mudclaw was a WindClan warrior that wanted to be deputy, and disobeyed StarClan's order. The night he got struck by lightning was when he messed with Brambleclaw.
He was fighting with Brambleclaw and stuff, then all the sudden, StarClan made a tree fall on him. It was a gift to all the cats of the Clans. Thank StarClan he was NOT in control of WindClan. Mudclaw was a very power hungry cat some people think he is almost as bad as Tigerclaw/Tigerstar but I dissagree Tigerclaw/Tigerstar tried to wipe out ThunderClan.