So, we all know what happens when u press f3. BUT there are more things if u press them with something else.... F3+a Reloads all chunks(good when lagging) F3+d Resets the chat(very helpfull) F3+c Hold this for 20 seconds and MC will crash(Have fun!) F3+b Press to see the hitboxes of player, animals(also for arrows so you can see them easier) F3+h ( best in my opinion) Press, and open ur inventory go on a item and see how many durability is left!
You can apply here: http://guildcraft.org/applicationform/mod.1/form Make sure you meet all the requirements, and this will help you http://guildcraft.org/threads/how-to-make-an-appropriate-application.1238/ Good luck!