I was playing a game in Standard Brawl, and my opponent had a Realm-Scorcher Hellkite.
At some point, while I had a spell on the stack, they started spamming its ability without expending mana. With the set-up they had, they could tap their creatures for mana, but they didn't have to; the skill was free for no reason.
They had Agatha, which can reduce the cost of abilities, but it cannot reduce it under to 0, and she was only at 1 power anyway...
I was playing a game in Standard Brawl, and my opponent had a Realm-Scorcher Hellkite.
At some point, while I had a spell on the stack, they started spamming its ability without expending mana. With the set-up they had, they could tap their creatures for mana, but they didn't have to; the skill was free for no reason.
They had Agatha, which can reduce the cost of abilities, but it cannot reduce it under to 0, and she was only at 1 power anyway...