What determines whose Global spell sticks?

[Kristoffer O]

A newly cast global will

1: Take up a free slot (out of five possible).
2: Overtake the same global from another player regardless of global slots occupied by spells.
3: Dispel a random global slot and take that slot even if it was previously yours.

Events that might cause discrepancies:
* Someone casts a global spell. It might take place before your spell taking up a slot so your spell must dispel another spell.
* Someone casts dispel. The dispel might and might not take place before your global is cast. Thus you might replace a global and afterwards another global is dispelled giving a total of four spells.
* The caster of a spell might die. This usually happens after spellcasting. A global can replace another and then the caster dies in a battle giving four remaining globals.