Are shadow cards only discarded at the end of the combat phase? If an enemy gets dealt one during the refresh phase, it would stay there until the next round's combat phase, correct?

I cannot really recall what would deal a shadow card in the refresh phase but it should stay there until the end of the next combat phase or after the enemy has made an out-of-order attack; whichever comes first.

Okay cool. It was in Dunland Trap.

MIght have been a combo from The Road to Tharbad Time forced effect and Boar Clan Warrior forced effect

Sorry, I was on my phone and couldn't elaborate for those curious. It was indeed that very combo.