Targeted fixes for the Arcanum Class Pack:

• Chaos Armour: Aegis no longer leaks the armour's damage-negation chance (the old temporary value is removed before the boosted one is added). Previously a monster whose armour was Aegis-boosted kept the negation chance forever after the armour wore off, making it effectively invulnerable at high levels.
• Chaos Armour: expiry no longer throws a Lua error from a leftover cleanup call to a non-existent value, which aborted the effect cleanup and the actor's turn.

Requires the Arcanum Class Pack (arcanum) addon; does not alter any other part of the class pack. More fixes may be added here later.