Here is the script below:
ScriptName BSUndineWaterHealingScriptShort RegenOnShort RainGenOnBegin ScriptEffectStart RemoveSpell BSUndineRegenWater RemoveSpell BSUndineRegenRainEndBegin ScriptEffectUpdate If RegenOn == 0 If IsSwimming == 1 RemoveSpell BSUndineRegenWater AddSpell BSUndineRegenWater Set RegenOn to 1 EndIf Else If IsSwimming == 0 RemoveSpell BSUndineRegenWater Set RegenOn to 0 EndIf EndIf If RainGenOn == 0 If IsInInterior == 0 If IsRaining == 1 && IsSwimming == 0 RemoveSpell BSUndineRegenRain AddSpell BSUndineRegenRain Set RainGenOn to 1 EndIf EndIf Else If IsRaining == 0 || IsInInterior == 1 RemoveSpell BSUndineRegenRain Set RainGenOn to 0 EndIf EndIfEndBegin ScriptEffectFinish RemoveSpell BSUndineRegenWater RemoveSpell BSUndineRegenRainEnd