EE2 Philosopher's Stone
The Philosopher's Stone is used to transmute blocks and craft high-EMC items from the EE2 mod. It is required in almost all EE2 fuel recipes. To charge it, press 'V' while combining with Shift will reduce the charge. Each charge level has a different transformation range for converting blocks. You can press 'R' to release a charge from the Philosopher's Stone which uses EMC from a EE2 fuel (or coal) and transforms a monster into another monster with the same class (hostile to hostile, neutral to neutral, etc.). You can find all recipes which use the stone with a right click on NEI's Recipe Mode in Tekkit Classic.
Philosopher's Stone Recipe
Place a glowstone, then redstone, then glowstone on the top and bottom row. In the central row; use redstone then diamond then redstone.

Philosopher's Stone Video