This is Trial level 3, "Teach me Bombers and Blockers". You have 10 lemmings, but only need to save 1 of them. Once again, you have 10 minutes, more than you'll ever need. Press X to start the level.
Your lemmings will come out the floating doorway in the upper-left corner. They will navigate rightward through a narrow passage. Your goal is in the lower-right area of this map. You can use the right analog stick to scroll if you want to see it.
As your lemmings walk right, you'll notice there is a bone in their path. The lemmings will treat this as a solid wall, so we'll need to find a way through. You have two new abilities at your disposal, the Bomber and the Blocker. The Bomber will be selected by default, but we want to use R1 to switch to the Blocker (lemming holding out it's hands.) When a lemming is close to the bone, target it and press X to change it into a blocker. Other lemmings will not pass a blocker.
Now that you have a blocker next to the bone, press the L1 button to switch back to the Bomber ability. Select the Blocker lemming and press X to change him into a Bomber.
You'll see a countdown timer appear above the lemmings head. it will count down for 5 seconds.
When the countdown reaches 0, your lemming will say "OH NO!"
Then the lemming will explode, taking out material around him when he dies. Lemmings that are close will not get damaged by this.
The explosion should have opened a pathway through the bone. Now your lemmings can continue down the narrow passage.
Further down the passage, you'll find another bone. Change a lemming into a blocker right next to it.
Now change that lemming into a bomber.
The explosion should have broke a hole in the bone. The lemmings will be free to continue on again.
You'll see a spiky blade in the path ahead. This will kill your lemmings. To avoid this, change the lead lemming into a blocker before it reaches the trap.
Make this lemming a bomber.
The lemming will explode, taking out part of the ground under him. The rest of the lemmings should now fall before reaching the trap. They will continue right and make a second fall.
There's another problem here though. If the lemmings keep walking right, they'll end up walking off this platform, then turn around and fall in the water, which kills lemmings instantly. What you'll want to do is turn the lead lemming into a blocker.
Your other lemmings will walk back and forth, between the wall on the left and your blocker. You'll notice they can't quite reach the goal.
Change a lemming into a blocker somewhere above the goal.
Set him as a Bomber.
Now the lemmings can get down to the goal.
Success! As long as one lemming made it out alive your good! Press X to continue to the fourth level.