Help with an ability trigger

Is there way make ability was trying to put in my make like a summon but have an 5% will make a summon unit?|||Randomize(20) make that 5% probability



Summon

Events

Unidad - Unit starts an ability effect

Conditions

(Ability being cast) = summon water elemental //set this spell to cannot summon any unit, a fake summon spell.

Acciones

Set temp_point = (Position of (Casting unit))

Set money = (Random integer number between 1 and 20)

If (money equal to 5) then

Unidad - Create 1 dummy caster for (Owner of (Casting unit)) at temp_point facing temp_point

Unidad - Add true summon water elemental to (Last created unit)

Unidad - Order (Last created unit) to Human Archmage: summon water elemental

Unidad - Add a 1.00 second generic expiration timer to (Last created unit)

Custom script: call RemoveLocation(udg_temp_point)

Else do nothing