Ranger ability

[MunchkinMan]

The general rule, as explained in the rules, is that to power a Class or Race ability that requires discards, you can discard cards from those cards you have in play (except the Class or Race that gives you the ability), or from those cards in your hand.

There are exceptions, of course, like the Cleric's resurrection or the Wizard's charm spell, which require the cards to come from the hand, but those are noted on the cards, like almost every good rules exception should. The Ranger doesn't specify an exception to the general rule, so you can use cards from either those you have in play (except your Ranger Class), and those you have in your hand.