Guild Wars 2

gw2 wiki say : Player tests suggest a five-second cooldown, although the tool tip says it is two seconds (Could be affected by the 30% chance to proc.)

is it real?

Your best bet to test would be to go to the HotM and equip a high crit chance build with two of the sigils in a set of weapons that have a very fast hit rate. D/d thief with death blossom, p/p thief with unload, or (probably the best) a p/p engine using a flamethrower. All 3 of these, as well as a few others, can crit 3-5 times per second. With two sigils that’s a 60% chance on crit which will surely happen once a second. So test it a few mins and see how often you’re able to leech. I can test it in a little while and let you know my findings if you don’t have the time or the right professions.

Tman.6349:

Your best bet to test would be to go to the HotM and equip a high crit chance build with two of the sigils in a set of weapons that have a very fast hit rate. D/d thief with death blossom, p/p thief with unload, or (probably the best) a p/p engine using a flamethrower. All 3 of these, as well as a few others, can crit 3-5 times per second. With two sigils that’s a 60% chance on crit which will surely happen once a second. So test it a few mins and see how often you’re able to leech. I can test it in a little while and let you know my findings if you don’t have the time or the right professions.

The problem with that is finding something to deal enough damage to you for the sigil’s heal to show up.

Doing something similar under a contested Grenth temple in Orr might be another option.

There are damaging mobs in the mists.