Guild Wars 2

Use any “On heal gain swiftness” rune set.
Get a costume potion such as “Cold Potion”
toggle in and out of costume and u get the on heal swiftness.

this workign as intended?

Adding a link to your other thread here as interesting points are being discussed there as well.
https://forum-en.gw2archive.eu/forum/professions/mesmer/Free-swiftness-on-demand-bug

edit
Also, activating or stowing the Med Kit with an Engineer triggers on-heal effects of runes as Alissah mentioned it actually triggering via "using skill #6” and not requiring an actual heal to be performed.

Also evidenced by the fact that using the kit’s five skills does not trigger the on-heal effects as the #6 skill is not being used despite healing actually being done via those skills.