Whenever a nontoken creature you control enters, you may pay . If you do, create a token that's a copy of that creature, except it has haste and "At the beginning of the end step, sacrifice this permanent."
Whenever a nontoken creature comes into play under your control, you may pay . If you do, put a token into play that's a copy of that creature. That token has haste and "At end of turn, sacrifice this permanent."
To crack a mirror is to provide an opening for the reflection to escape.