Three-on-one doesn't seem like a fair fight, but we'll show you how to turn the Ruin Sentinels boss fight into a cake walk. The trick is to fight them one at a time. Kill the first one on the platform you start on, then wait for the second one to hop up.
Once he does, put as much damage on him as you can until the third joins the party, then hop down to the arena below. Divide and conquer! See exactly how to avoid instant death in the Ruin Sentinels boss fight video above.
For more help be sure to check out our complete Dark Souls 2 Boss guide.