What should we do with ISIS?

[swl]

Get rid of them. There are a lot of bad people in the area but the Islamic State are the worst of the worst.

Everyone should ally against them. That does not mean that everyone is suddenly going to become best friends, but we need a temporary alliance.

Fully support the Kurds, they are the best guys there. They will probably use everything we give them to create their own State later but whatever, they deserve it.
Get rid of Maliki (done), because he is just terrible and is partly responsible for the sectarian tensions, and fully support the new Iraqi government.
Temporarily shut up about Assad, and hope he will later end up assassinated by a bodyguard or something like that. Let Iran intervene if they wish to.
Do whatever is possible to prepare peace for the after-ISIS, because it is likely that many will try to have their revenge against the Sunnis who accepted the Islamic State.