Does a creature with "ablaze" or "growth" still get to keep increasing its stats after a quintessence has been used on it?
Also, otyughs increase in stats even after quint has been used.
Technically, you have to target the 'immaterial' creature to use its ability, so I think these are additional loopholes.
No, because they are not 'targets'. The ability applies only to the creature itself, ie, the target is self.
Growth abilities continue to work when a creature has been immortalized.
Personally - taking this discussion back to your card idea - I think that a card which removes immortal status from a single creature should be implemented. Think about it.
If a player desperately wants to make a creature of his immortal he has to include Quintessences in his deck and therefore 'slowing' the deck down.
If you are afraid/want to counter an immortal creature, you could include Mortality, therefore both of your decks are 'slowed' down. This way, it will simply be a matter of luck/card shuffle/hands on depending who gets the Immortality/Mortality cards in their hands.
If a player happens to get an early Elite Otyugh with Quintessence, your only defense - well, there is no defense.
1)Your only option would be to get a Lava Destroyer (something with Growth) on the table and then to likewise Quintessence it.
2)Or, alternatively, to carry a few blessings/chaos powers to make your Lava Destroyer have more HP than the Otyugh.
3)Even more desperately, bring out 2 or more creatures in one turn and hope the Otyugh is distracted in removing the first two, giving you time to grow the 3rd beyond the Otyughs hp.
In the second scenario, there are numerous cards which can just as easily reduce the Destroyers HP making him just another meal for the Otyugh. Firebolt, Lightning, Icebolt, Drain Life... to name a few.
The third scenario is entirely dependent on whether you are fighting the AI or a player.
In conclusion, the game desperately needs something to counter Immortality.
@Bobcamel. If immortality is a status which removes the criteria that a creature can be targeted. Surely the game mechanics must check for immortality. If this is the case, surely a spell like Mortality could be made to
only target creatures with the Immortality status.