Holding V while holding a Philosopher's Stone will charge it, and the durability bar will go up. While the stone is charged, press R to release a charge, If this hits a mob, it will take a glowstone dust out of your inventory and turn it into a random different mob, remembering if the mob was passive or aggressive. Pressing C will open a 3x3 crafting grid, but be warned, do not put the stone into this inventory, if you want to do that use a real crafting table. You can also right click or shift+right click to change blocks around you. The blocks that can be changed are below.
|Right click||Shift + Right click|
|Stone ⇒ Cobblestone||Stone ⇒ Grass|
|Cobblestone ⇒ Stone||Cobblestone ⇒ Grass|
|Grass ⇒ Sand||Grass ⇒ Cobblestone|
|Sand ⇒ Grass||Sand ⇒ Cobblestone|
|Gravel ⇒ Sandstone||Sandstone ⇒ Gravel|