Looking for an Auto-Cast ability with certain AI in it...

Looking for an Auto-Cast ability with certain AI in it...

Hi,
I'm looking for an Auto-Cast ability that 12 towers with cast again and again on 1 without stopping. Currently I'm using slow but only 3 towers will cast at a time and they wait for the slow buff to expire. Thanks.

Edit: I just had the idea to use fire arrow, but my aim was to have no attack at all on the unit just the auto-cast being its attack.

Is the Slow effect important? I'm pretty sure that none of the non-attack-enhancing autocast abilities will be automatically re-cast if the unit still has the buff, but you could make the buff last 0.01 seconds if it itself isn't needed.

Otherwise, I reckon you'll need to look into triggers.