Elemental Spirits have perpetuation costs associated with their level. Auto-Refresh traits from summoner subtract from these base values, represented in parentheses.
1~18: 1 MP/3 seconds
19~24: 2 MP/3 seconds
25~37: 2 (1) MP/3 seconds
38~56: 3 (2) MP/3 seconds
57~74: 4 (3) MP/3 seconds
75~80: 5 (4) MP/3 seconds
81~89: 6 (5) MP/3 seconds
90: 6 (4) MP/3 seconds
91~99: 7 (5) MP/3 seconds
Elemental Spirits cast spells based on observable priorities:
Casts Curaga IV or Cure V if the HP of a party member is in the orange or red. It seems to favor this over Cure V at high levels, and often casts Curaga IV on its Summoner even if the Summoner is solo.
Can cast Curaga IV on another party in its summoner's alliance.
Casts Holy/Holy II, Banish I - Banish IV, Flash, and Dia/Dia II when used to fight against an enemy, depending on Light Spirit's level. It can cast Cure V on a single party member whose HP is in the orange or red, even if Light Spirit is currently engaging a target.
Cannot cure, enhance, or otherwise target itself in any way.