I would copy and paste the questbook intro here but you don't need to read it twice. To summarize, back in 1.7.10, my and my friend made a custom modpack and the goal was infinity ingots - as you can guess we never got there. Later i decided to make a pack with HQM and such and it was a horrible failure. this is the 1.12.2 continuation and legacy of "OPCraft" (that's what we called it) but this time, you can actually follow the quests.
Its definitely not an expert pack, in fact its very easy and I highly suggest it if you are a beginner or intermediate player. You can play following the quests or you can play it just like any other 'kitchen sink' modpack. There's around 180 mods and you will probably need to boost your allocated memory a bit. Its mostly based around using EMC from ProjectE to make Avaritia's insane items achievable.
Unfortunately, there's a lot of mods that aren't used in the infinity catalyst crafting recipe and don't appear in the quests. I plan on expanding it out to have a 'World S' set of quests that are unlocked after making an infinity catalyst, but it may be a while.
A few mods in the pack:
Actually Additions by Ellpeck
Applied Energistics 2 by AlgorithmX2
Astral Sorcery by HellFirePvP
Avaritia by brandon3055
Better Builder's Wands by Portablejim
Blood Magic by WayofTime
Botania by Vazkii
Draconic Evolution by brandon3055
Ender IO by CrazyPants
Extra Utilities by RWTema
IndustrialCraft by Player
Mekanism by aidancbrady
Mystical Agriculture by BlakeBr0
Ore Excavation by Funwayguy
ProjectE by sinkillerj
RFTools by McJty
Thaumcraft by azanor
Thermal Expansion by TeamCoFH
Tinkers' Construct by mDiyo
And many much very more...