Risen Executioner can't block.
Other Zombie creatures you control get +1/+1.
You may cast Risen Executioner from your graveyard if you paymore to cast it for each other creature card in your graveyard.
2/25/2015 Risen Executioner’s last ability doesn’t change when you can cast it.
2/25/2015 Once you start to cast Risen Executioner from your graveyard, you’ll finish casting it, including paying its cost, before any player receives priority. No one can respond in time to affect the cost you’ll pay (perhaps by destroying one of your other creatures).