You have an infinite combo here, so as much as you want. As long as you can keep paying the cost of putting a -1/-1 counter on the Devoted Druid , you can keep making mana and 1/1 elf tokens. The tokens will pump the Druid since they share a creature type with Coat of Arms , which will let you put another -1/-1 counter on the druid, etc.
October 4, 2014 11:58 a.m.
October 4, 2014 1:39 p.m.
Coat of Arms is the more game-ending card. All those Elf tokens will pump each other too, so you'd have 1000 1000/1000 elf tokens.
If all you want is the mana, Sigil of the Nayan Gods is easier to cast.