Legendary Rule Question

[TreeTopSky]

Let's say I have a {Leyline of Singularity} on the battlefield and 1 {Snapcaster Mage}.

I cast a 2nd {Snapcaster Mage}, does this creatures ability trigger first, or am i required to sacrifice first? Also, under the case of me sacrificing, if i choose to sacrifice the newly cast snapcaster, does it's trigger enter the stack?

[griffin131]

To clarify, you're not sacrificing - you just put one of them in the graveyard. The difference isn't relevant to your question, but it can be relevant.

If a 2nd Snapcaster comes into play, before the ETB can be put on the stack you have to choose one to keep.
After you resolve that state based action the ETB of the newest Snapcaster will still fire - even if you chose to keep the old one.

[TreeTopSky]

To clarify, you're not sacrificing - you just put one of them in the graveyard. The difference isn't relevant to your question, but it can be relevant.

If a 2nd Snapcaster comes into play, before the ETB can be put on the stack you have to choose one to keep.
After you resolve that state based action the ETB of the newest Snapcaster will still fire - even if you chose to keep the old one.

Ok, thank you for the help. Cleared up a bunch of stuff.