How to stop Submarine attacking last units?

[Marshmalo]

Hi, I have a problem with a Submarine unit im designing, Obviously it uses torpedoes to attack ships but it also attacks land units like buildings and troops, is there a way so I can make it attack only Floating units?

I would set it to an Ancient or Snapper but I'm already using those unit classifications for other targeting uses.

Also how can I make it permanently invisible even when it attacks?

I want it to be very similar to how the Submarines work in WC2.

 

[Chaosy]

if it is a triggered spell use

• Or - Any (Conditions) are true
  • Conditions
    • (Unit-type of (Target unit of ability being cast)) Equal to Footman

you can make the floating units "mechaical" and only allow it as target.

 

[Spartipilo]

To make it permanent invisible you have to abuse of Warcraft systems

Apiv, Agho, Aeth (Permanent Invisibility, Ghost, Ghost Visible): These abilities make units invisible without the tradeoffs of setting them invisible with triggers. Often this is a better solution than pausing units or adding locust. Units with permanent invisibility will lose their invisibility temporarily while they are attacking. So the ability can be used to create units like spirit wolfs at level three. Units that have both Permanent Invisibility and Ghost stay hidden, even while they are attacking. The Aeye (Sentry Ward) spell adds permanent invisibility to the summoned unit automatically by the way.

A full ability guide to achieve uncommon stuff can be found in: http://www.wc3c.net/showthread.php?t=81742