Replied to your Tweet but here as well:
Use a “Mirror Vector by Normal” node. The vector is the velocity (or direction) of your grenade. The normal is the wall normal (you’re on “impact normal” in the screenshot).
Then I guess you’d want to set the velocity to the new vector. Also, if it was me, I’d be saving the current velocity to a variable and adding that on to the location right at the end, rather than trying to plug in reflection stuff directly into the “set location”.
- If you’re trying for Quake style, I think they’ll reduce the XY velocity on the bounce - but don’t quote me on that.
**Edit: **As far as I can tell you’ve got the maths right, but you should be plugged in to “Normal” not “Impact normal”.