Water Ball

Water Ball
Max Level: 5
Type: Offensive
SP Cost: 15 + 5*(SkillLV/2 rounded down)
Target: Enemy
Range: 9 cells
Cast Time: SkillLV sec
Cool Down: None
Duration: Instant
Effect: Hits the target up to LV*LV-1 times with a Water elemental attack of (100+30*SkillLV)% MATK. You must stand on water or on a Deluge (Sage skill) cell to successfully use this spell.
The damage for each hit is calculated individually and the damage numbers do not show as adding up, also casting Lex Aeterna (Priest Skill) on the target will only affect the first hit.
This is the strongest single target spell in-game. The number of water balls that you are actually able cast also depends on the amount of water you are standing in.
In any given X by X grid, the game determines that you are surrounded by (X*X)-1 cells. So, at level 4/5 Waterball, you can cast up to (5*5)-1, or 24 water balls.
However, if you're only standing in a 3x3 pool, you will only cast 8 water balls. If you're standing in a freaky grid (like a partially-used Deluge), the number of balls cast is equal to the number of water-occupied cells in your grid, so if you're in a cell like this:
O = empty
X = water
* = player
OOOOO
OOOOO
XX*XX
OOOOO
OOOOO
...you'll only cast 4 water balls with level 4/5. With level 2/3, you'll only cast 2 water balls, since only 2 are in the 3x3 grid surrounding you.
This is particularly useful to keep in mind when you're with a Deluge Sage, since Waterball uses up the Deluge cells.
You can determine which cells are used by how you stand in the cast area (every cast will wipe out the respective grid section around you, centered on you), and maximize the effectiveness of the water ball spells you cast.
[LV 1] 1 Waterball / 1x1 Grid, 130% MATK
[LV 2] 3 Waterball / 3x3 Grid, 160% MATK
[LV 3] 8 Waterball / 3x3 Grid, 190% MATK
[LV 4] 15 Waterball / 5x5 Grid, 220% MATK
[LV 5] 24 Waterball / 5x5 Grid, 250% MATK