And his heroics could be needed this weekend as they face a Scotland side that lost their opening game with England but showed glimpses of their attacking threat throughout.
But it isn't just Halfpenny's presence that could lift Wales to a win at the Millennium Stadium on Sunday when it really matters, according to Llewellyn.
"We've got a very intimidating set of backs at the moment, as big as any backline in world rugby, I would suggest," he said.
"And the more time they have together the better they'll get.
"So to have someone like Hooky [James Hooky] on the bench is a bit of a bonus really.
"He can't force his way into the team, but I've never seen in recent times as many match-winners across the park - guys like George North, [Alex] Cuthbert, Jamie Roberts, Warburton, [Toby] Faletau in the back row, Gethin Jenkins coming back in [at prop].
"We're not just dependent on one or two players to do something special for us.
"We've got them right across the park now so I think we're looking as dangerous as we ever have."