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New Legendary Cards - Aviana and Anub'Arak
Aviana: 9 mana 5/5. Your minions cost 1
http://media.blizzard.com/hearthstone/images/the-grand-tournament/cards/aviana/en-us-full.png
Anub'Arak: 9 mana 8/4. Deathrattle: Return this to your hand and summon a 4/4 nerubian
http://media.blizzard.com/hearthstone/images/the-grand-tournament/cards/anubarak/en-us-full.png
Daxxarri
Okay, so, Aviana makes minions cost 1 while she's in effect. What if a Mana Wraith or Nerub'ar Weblord is in play? How about a Pint-Sized Summoner or a Venture Co. Mercenary? How about all 4? Which minion's effect takes precedence? Do they all stack? Why? If not, why not?
In my opinion, it's much more elegant to simply apply the effects in the order in which the cards take effect.
Daxxarri
It depends on the order of play. So, a minion costs 0 (For whatever reason, Molten Giants, Thaurissan, etc.), then Aviana hits the board, setting minion cost to 1.
Alternatively, Aviana is on the board, so all your minions cost 1, then Thaurissan is played and takes effect, so they all become 0.