In this Brawl battle I was unable to cast creatures from my hand for their emerge cost, as Herigast normally allows you to do. Normally, cityscape leveler would have a 0 cost option that would allow me to sacrifice Herigast to pay for 9 generic mana of CL's casting cost, rendering it a free spell (so to speak). I don't see anything on the battlefield that prevents alternate costs or anything. My opponent is has the following cards on the field:

Battlefly swarm
Unscrupulous agent
Gix, Yawgmoth Praetor
Massacre Girl, known killer
Aclaszots, Deepest Betrayel

Thanks!