×You need all 12 mirrors.

×I have discovered that with some of the arrangements that involve cutting the mud ahead of time, you can trap a baby off to the side for later. That still leaves me two short though. I've also tried arrangements that involve getting all 12 mirrors next to the tar if that's all the hint above was getting at. Still isn't getting the job done though.

×Skell's idea generator: http://forum.caravelgames.com/ideasGenerator/view
Challenges Scoreboard: http://forum.caravelgames.com/challenges.php
Level map viewer: http://forum.caravelgames.com/map.php
Tactical DROD game: http://forum.caravelgames.com/tsspreview.php
(Note: Requires Flash)
Room Element Search tool http://forum.caravelgames.com/roomsearch.php
(Search through all published holds for rooms with various elements.)
Room position Heat Map http://forum.caravelgames.com/heatmap.php
DROD has a wiki! http://drod.wikia.com/wiki/Deadly_Rooms_Of_Death_Wiki
Skell's super cool list of turn sequence stuff https://docs.google.com/document/d/1QS9Vk3xsd4jlGF23J8p7c2IM5cmhwmoe6eCEaaAn8jY/edit#heading=h.ocovx14zokm4

It's not listed in "help", but [attachment] will embed the whatever image is attached to a post.

×I had a 2-by-3 blob and a 2-by-2 blob, with mirrors at the corners to prevent them from growing bigger. The rest of the mirrors were in the shallow water.

If you need more than that, I can take a screenshot of my arrangement.

×So you have 12 mirrors, but you need 13 babies per spawn. Because pushing mirrors onto shallow water will always give you 1 baby per mirror, at somewhere around you need to get 2 babies with a mirror.