Playing a reaction spell on your own turn is a pretty cool trick -- you can do things like this:
1. play an Anchornaut on your side.
2. use its ability to kill itself.
3. play Summon Sleeping Widows as a reaction to its destruction.
Perhaps not the most cost-efficient way to pull that off, but still a surprise for your opponent :-)
This allows you to attack with the widows in the same turn.