If SP reaches 0, nothing happens, but you aren't able to do anything that requires SP until it is restored.
Max SP is determined by ((character level * magic) + 80) * 0.9 for players from the diamond, ruby or sapphire hordes.
- these players generate maxSP/1440 SP per minute
Max SP for a player in the emerald horde is determined by (character level * magic) + 80
- these players generate maxSP/1200 DP per minute
Spell point restoration
- levelling up fills your HP and SP to max
- drinking mana potions increases current SP isntantly
- resting divides the base regeneration time by 3