Last saturday in an Standard test game, my opponent tries to Selesnya Charm my Purphoros, God of the Forge, going for the exile. in response I Magma Jet one of my creatures to get rid of my devotion.
My opponent tells me that Purphoros, God of the Forge is still exiled, because that's how it works on MTGO. While I'm like: “it's no longer a creature, so it's not a legal target for the charm”.

We both want to know what the correct ruling is.

It's not exiled.

Selesnya Charm has one target when cast using the “exile target creature with power 5 or more” mode. Upon resolution, you check if the target still satisfies those criteria. The God is no longer a creature, so the target is illegal and Selesnya Charm is countered.

Daniel Kitachewsky
L3, Paris, France
Rules NetRep