Master of Cruelties, Riot Piker

[X9xCRUSHERx4X]

This may be a dumb question, but say I have a {master of cruelties} and a {riot piker} on the field, who would cancel who out?

Modded the subject for searching purposes.  -Mike

[X9xCRUSHERx4X]

Thanks, me and my friends have been arguing for weeks about this

[Keyeto]

{Master of Cruelties} would not be able to attack, according to one of his Gatherer rulings:

4/15/2013 Master of Cruelties isn't forced to attack, but if it does, it must do so alone. If you control another creature with an ability that says it must attack if able, that creature must attack and Master of Cruelties won't be able to.

[Mikefrompluto]

Aahh! Removed my comment to avoid confusion.