How to create a simple trap

[voodoo]

I know this has been asked before, I spent more than one hour trying to find the answer in this forum, the wiki, the video tutorials but couldn't find an answer to my woes.
I want to create a simple trap : a boulder trap : dexterity save vs DC 10, take 2D4 damage or half damage if the save is made.
I created an NPC "boulder trap", added a trait "+2d4 bludgeoning damage; DC 10 dexterity saving throw" but couldn't find a way to link the saving throw to the damage so a simple double click would automatically "attack" my characters.
I even typed a line "Trap [M] [SAVEVS: dexterity 10 (H)] [DMG: 2d4 bludgeoning] which wasn't even recognized.
I'm quite desperate, any help would be greatly appreciated :)

On a side note, is there a way to have this attack go against all the characters in one action. I think I saw this done in a tutorial but can't find it again.

[Zacchaeus]

Hi, voodoo and welcome to the forums.

The best way is to create an NPC called trap. All you need is to create one action for it (i.e. you don't need any other stats etc). The wording of the action is important so copy what I've written below and then edit it to suit your needs.

The target must make a DC 15 dexterity saving throw or take 2d6 poison damage or half as much damage on a successful saving throw.

[voodoo]

Thank you so much!
One of the reasons I bought FG was that the community was supposed to be very helpful and welcoming but I didn't expect such a prompt and clear response!
Thank you again, Zaccheus.

[Nylanfs]

Whose been spreading such slanderous lies about us being helpful! :)

[LordEntrails]

This post has a sample trap I've created; https://www.fantasygrounds.com/forums/showthread.php?24613-Hazards-amp-Traps&p=215995&viewfull=1#post215995

[DarthSinistris]

I"m four years late, but thanks for this!

[LordEntrails]

My mom taught me it's never too late to say Thanks :)