This has happened to at least 20 times now, and it really hurts because my new deck (borrowed and adapted from the fg farming decks posted here) has only a few key creatures in it (elite otyugh/elite ffq/fallen druid) and quintessence is fundamental to my strategy so it's quite a match breaker.
When I use quintessence on one of my creatures, like an otyugh, it often doesn't seem to register for the other player. The creature ends up getting killed by firebolts, lightnings, etc., devoured by other creatures, mutated, lobotomized, or reversed: something which should never happen. I've begun to take screenshots of how my creatures have immortality before they die just to show the other player and show the players I chat with, "see, I told you so!"
I generally play quintessence immediately after playing my creature in the same turn. This also seems to be the most problematic, however. The bug seems to occur less frequently (so far not at all) if I play the creature in one turn and then quintessence on the next turn, so sometimes I've even waited a turn, unnecessarily taking a risk, to play quintessence on the next turn even though I could have played it on the same turn.
This never happens to me against the AI, only in pvp, so I would attribute it to a desync bug. However, it occurs so frequently that perhaps there is an issue with quintessence itself and this does not precede the more rare but obvious desync bugs (player health changing randomly up or down in spite of not healing/being damaged, creatures going to 0/0, etc).
The frequency with which this happens for me may also be attributed to the fact that I am in Japan and hence, in spite of having a pretty nice broadband connection, may not always have the best connection with other clients or to the server (I'm not sure if the game is hosted on a central server or, if in pvp, one of the two players' machines are used as the host).
I have to say that in pvp, more times than not, my immortal creatures are killed rather than lasting as they should. It's really a deal breaker when I go against a shrieker rush deck and have an elite otyugh with quintessence out before any shriekers/graboids come and still end up having it gravity pulled/reversed when I put quintessence on it - so much so that in spite of my deck performing very well in pvp when this bug doesn't occur (I have very few losses in the absence of this glitch), I'm considering changing decks for the time being to something that doesn't depend on quintessence for pvp matches (ex: speed poison).
