Loss of Lemmings: Zero
Make the 5th Lemming an Attractor, then make the one that drops in the pit Throw from just right of the centre of the pit. Use more Throws to build this into a ramp running up to the right edge of the pit. The last stone thrown will be one pixel above the pit floor level. Fill to the right while standing left of the stones, and the Lemming will walk free up to the right. Now make a ramp of stones by using Throws going right, using the join between the big and small steel blocks as a timing mark. Jump a couple of other Lemmings out of the attractor's spell to assist with this process. When the last stone is placed, Jump all but one back into the dancing horde. Fill under the stone from the outside, then Fill again while standing on the previous fill. Release the attractor. Fence through to the exit if necessary, stopping the fencer by making it a Jumper or Thrower.