Rosenna, Thief-Princess

As Rosenna, Thief-Princess enters the battlefield, choose odd or even.
Whenever an opponent casts a spell with an odd converted mana cost, if you chose odd, create a
1/1 black Rogue creature token.
Whenever an opponent casts a spell with an even converted mana cost, if you chose even, create
a Treasure token.
"Good servants are well rewarded."