Serene Steward drains 1 mana from your hand and gives your first creature +1/+1, whenever you gain life.
It seems like it should combo pretty well with Elfhame Druid (whenever a card you control drains mana from your hand, gain 3 mana) or Hallar the Firefletcher (whenever a card you control drains mana from your hand, Hallar gets +1/+1 and deals 2 damage to opponent).
Testing it out, however, quickly revealed to me that whenever you have Serene Steward and either Elfhame Druid or Hallar in play, and then gain life, the game will permanently stall out and you’ll be forced to quit the match.
I suppose elfhame and hallar are supposed to trigger with the new manadrain mechanic ( “kick” in the paper version). I’m not sure they were also supposed to work with the older drain effects (some interactions could be quite nasty actually).
That doesnt explain the bug by itself but it might have something to do with it.
I checked Hallar, with both tetzimoc and rhonas’s last stand and when tetzimoc drains the Mana to give an enemy creature -1/-1 the game freezes, while the Mana drain from rhonas’s last stand is managed correctly
It looks like it works fine when you get drained by an effect on playing a card. However, it seems to bug when the drain comes from an ability meant to be triggered several times.
I suppose it wasn’t meant to work with abilities so that’s fair enough … Anyway, a solution has to be found in order to avoid the game freeze in this particular case.