Guild Wars 2

https://www.reddit.com/r/Guildwars2/comments/6u622i/patch_notes_16_august_2017/dlq7r9l/

if you have the signet trait, put a signet in the right-most utility slot (9). Then move it to the middle slot (8). It gains a stack of the buff if you do this. Then move it to the left-most slot (7), it gains another stack for a total of 3 stacks. You can do this with another signet and put it in the middle slot to get 2 stacks. Tons of free power or condition damage.
It might not show up in your buff bar, but look at your hero pannel stats

I wondered why some guards seem to be able to soak unreal damage, like 4v1 and still not going down.

Admittedly, I assumed it was deliberate on ANET’s part.

Shouldn’t work in pvp considering the locked skill bar and reset before game start.

You’d do it in the cage prior to the match. As long as you didn’t use the signet on active, it would presumably stay up.

In PvP, it stays until you die and respawn. Once you respawn you can’t change your utilities around so the bug is a bit worthless in spvp.

Worthless? to triple stack signet effects? That could easily win a mid fight. I had wondered about the seemingly unkillable trap gurads.