The green line shows the main loop you'll have to navigate several times to finish this puzzle.
Grab the first 3 bombs and step into the "elevator". Grab a bomb at B, and get the pickaxe. This time through, light a bomb at A, just before the brick below phazes out (or you won't be far enough from the explosion). As you pass B, quickly grab another bomb and drop down to C. Light a bomb at C, grab the exposed treasure, and go right to the teleporter. (3 bombs left)
Follow the green line around, and be careful of the phaze brick at D. Stand on D and use the pickaxe on the ceiling to your right, and then you can go right. You won't need the pickaxe anymore, so you can drop it anywhere. Follow the green line around (use a bomb at E -- 2 left), and the follow the red line around and get the snare.
Follow the green line around again, using another bomb at E (1 left). Now get the treasure at K: Release monk J by zapping the turf beside him, then kill him by zapping a hole and standing on him after he falls in. You may have to kill him several times. Get the treasure by zapping the turf you zapped to release him, then climbing down the ladder and back up.
[The problem is, the monk you killed can create havoc later, depending on where he regenerates. I don't know a foolproof way around this, unless you want to cheat: Instead of releasing him, use the pickaxe over him (see the Bugs page) to hold him still while you get the treasure, and later when you bomb your way to the teleporter.]
Now, get bombs F and G if you haven't already (you should have 3 now), and light a bomb at L to clear the way to the teleporter. Quickly drop into the teleport (watch out for the monks you just released), and get ready to zap to your right immediately after teleportation.
If you're still alive, lure the monk up to the top of the ladder, and zap him into a hole there, climb back down, zap the 3 tiles labeled M, and jump into the hole. After falling through some trapdoors, immediately run one tile to your right and set the snare.
Light bombs at N and then O and pick up all the treasure revealed. You can now get back to the main elevator.
This time, grab the key. Go to B and get some bombs. (You may have to wait here for a while... Maybe that's why it's called "Castle Chronos".) Light a bomb at A, ... you know the routine by now. Make sure you have at least 2 bombs when you get to point C (3 if you already picked up the bomb at H), but an extra 1 or 2 might be helpful if there's a monk on the loose. Follow the green line all the way around to the teleporter, don't forget to zap to your right immediately again after you go through, and you're done.