Need help with mana degen effect trigger

[Maridot]

I'm trying to make a trigger that does this.

Set mana of (Picked Unit) to (Mana of (Picked Unit)) - 20

However I cant find how to add the - 20 to finalize the trigger, I can only find the selections up until

Set mana of (Picked Unit) to (Mana of (Picked Unit))

Any idea how I'd be able to fit that -20 inside one Action with the other stuff mentioned so far?

http://i.imgur.com/tyuNxxf.jpg

 

[LordDz]

Post the trigger so we can help you.

 

[Maridot]

Posted screenshot of the drain part of the trigger. I'm following a guide for making triggers but he doesn't mention how to browse to the variables he uses so I feel a bit lost with certain things.

 

[Wietlol]

No need for screenshots or triggers.
I understand exacly what he means.

GUI is very limited to one action per time. This is to avoid syntax errors.
Instead of the (Mana of (Picked Unit)), you want Arithmetic.
Thas function will let you combine integer/real values.
You will find your way from there.

EDIT: damn! still took me 12 minutes to actually upload an image

 

[Maridot]

No need for screenshots or triggers.
I understand exacly what he means.

GUI is very limited to one action per time. This is to avoid syntax errors.
Instead of the (Mana of (Picked Unit)), you want Arithmetic.
Thas function will let you combine integer/real values.
You will find your way from there.

Ah thank you both a lot for the help. It indeed does allow me to use "(Mana of (Picked Unit)) - x" when I change the first variable to unit mana. Thank you a bunch!