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Have a problem when using Radiant Flame in Xmage~~~
example: have 2 SpireBluff Canal and 1 Ather Hub untaped, i want to cast Radiant Flame for 3 damage~~
I click Radiant Flame first,and then tap 2 SpireBluff Canal and 1 Ather Hub,the system automatic cast the spell and only do 2 damage。 how to decide the color of mana? 1 SpireBluff Canal for red ,1 SpireBluff Canal for blue and Ather Hub for white??

You gotta manually tap. Tap the lands before hand and then click radiant flames and then click the mana in your mana pool in the info panel under your avatar.