Summon units

[0rcL0rd]

hi, i want to make a tower in my TD that is going to create 1 unit every 20 seconds, and the unit will only stay for 10-15 seconds.
But i want the ability only to start after its built offcourse.
can someone tell me how i can do this.

Tnx

 

[kaboo]

start
events - unit finishes construction
conditions - unit type of constructed unit equal to summoning tower
actions 
- add constructed unit to summoners {-unit group}

summon
events - every 20 seconds
conditions -
actions
-pick every unit in summoners and do actions
  - unit create 1 summon at position of picked unit for owner of picked unit
  - add expiration timer to last created unit that will expire in 10-15 seconds

something like this should