Go down the stairs. There are two hexagonal ledges in the lava pool. Hop to the right one and then jump to the next one on the right. Jump up to grab the two ledges above and pull up.

Turn left and jump to the opposite set of ledges. Now turn left to face the lava pool and jump on the two ledges below.

Wait for a few seconds and new ledges will rise up on your right. Walk on them and...

... jump to the ledges that just appeared on your left. Go around to the right.

A new single ledge rises up, so jump to it and finally jump on the safe blocks ahead.