A few people have asked whether Equivalent Exchange will be included in the modpack... it won't be.
The main reason is the fact that it is so overpowered and for many people just leads to them getting bored very quickly as they 'have everything'.
That said you cant deny that transmutation (changing one item into another) is extremely useful for building and means you don't have to store vast amounts of cobblestone, it also helps keep the world in a better state because people need to collect less materials.
With this in mind I decided to develop my own transmutation system within my main mod, using an item I called the 'Essence Stone'. You won't recognise all the ingredients in the recipe, the centre one is Diggyolite, the same ore used to craft the in game currency... maybe you can guess where the purple item is from (take a look at earlier previews)...
Only a selection of vanilla blocks and items can be transmuted, that way items such as wood from Biomes 'O' Plenty trees etc will still be of value when it comes to player trading via stores, malls etc and it gives players an incentive to go out and search for things and take the time to grow trees, crops etc. I looked through the vanilla items and recipes and got my kids to help decide which items should be transmutable and what the recipes should be so whilst it doesn't relate to the EMC values you know from Tekkit Classic we do feel it is a fairer and better balanced system, plus being developed by me we can make changes if we decide something should be added or changed!
Here's some example recipes, the 'Essence Stone' is always placed in the middle slot...
The stone has 640 uses (10 full stacks of items), with the damage value showing how many times it has been used so far, it cannot be repaired and after the 640th use it will vanish, so you will need a new one every so often. More than 50 transmutation recipes have been added along with several other standard crafting recipes including craftable and upgradable horse armor.
