Depending on who you're playing. I'm a Main Inquisitor player and i think Debronee is an old Hero so if you know his skills, then countering is fairly simple. Remember this, he is scary because of only 1 reason: Intensify. So your goal is to either:
1/ Avoid it completely while killing him (Stun, Silence, Invisibility... or a combination of those),
2/ Escape it by using Blink when he intensifies you (works MOST, but NOT ALL of the time.)
3/ Or live through it and counter attack: Hades Amor (very popular item), Helm of Divine Favor (Rarely seen due to its high price), Using CYCLOPS (His third skill relfects damage as well + Hades Amor = Deb is dead before he finish intensifying you ), Using Marithus (He can pretty much Harvest back the amount of HP lost easily if built correctly)
That's what i can think of now... so Have Fun!