SetCreeperInArea(<-area <-creeper <-probability <-isRound)

Sets creeper in area.
Area: A V4 specifying the lower left and upper right of an area.
Creeper: An int amount; 1000000 is equivalent to a creeper depth of 1.0, while -1000000 is equivalent to an anti-creeper depth of 1.0.
Probability: A float in the range of 0 to 1 indicating the probability creeper will be deposited in a cell.
IsRound: When true, the area specifies an elliptical area. When false, a rectangular area.

SetCreeperInArea(V4(5 10 20 20), 100 1000000 *, 0.5 true)