Payment is calculated using original casting cost, then adding additional costs, then deducting cost lowering effects.
Starting casting cost for frogmite : 4 (this is the so called converted mana cost, considering mana drain and stuff)
Additional casting cost because of sphere of resistance : +1
Deducted casting cost because of affinity : -5
This yields a payment of 0 (zero) mana for the frogmite. But remember though, while you pay zero mana for your 2/2 beatstick, George W. Bush will still find a way to tax you for the purchase of this creature.
:lol: :lol: :lol:
Ok, it's all right. I just wanted to point out that with trinisphere it is totally different: it is taken into account after everything else, so you won't ever be able to pay less than 3 mana. And to be exact, you
can cast an affinity spell for zero under Nether void, but it will be countered (maybe you only wanted to lower your hand size or rise the storm counter, who knows!), since this is the correct Nether Void's text: "Whenever a player plays a spell, counter it unless its controller pays
". It does not raise the cost in any way, it just requires an additional payment after the casting cost is paid.
