From [ http://forum.fallensword.com/viewtopic.php?t=46802 ]...
I don't know how many people know the history of the hell forge... so I will post it...

updateForgeially each forge level added 10% of each stat to the item as a forging bonus with the level 5 forging bonus being 50% increase to all item stats...

Then the max level increased, and HCS realized this would break the game at later levels so they nerfed it... the new system added +1 to each item stat with a +6 bonus at level 5 forging...

This change made the Hell Forge system useless later on in the game... and from this system and the one before the cost of 1 forge level was 10 PowerPoints or 50 PowerPoints for 5 levels of Hell Forging...

Pretty recently they introduced this new current system where you only pay 2 PowerPoints and a cost of gold determined by the level of the item multiplied by 150 and then 1 for the first forge level... then the cost would double for each forge level... resulting in a total of 10 PowerPoints and (4650 * the level of the item) gold... where if the level is less then 50, the cost for the item assumes it is a level 50 item... The bonuses to the new and current system are...

HellForge Action Page wrote:

[Level 1] +5 to stat points, +2% to enhancements [Level 2] +10 to stat points, +4% to enhancements [Level 3] +15 to stat points, +6% to enhancements [Level 4] +25 to stat points, +8% to enhancements [Level 5] +50 to stat points, +10% to enhancements

Now at first this seems great... especially compared to the last system because the max no of stats affected by forging is 6 so an item with those 6 stats under the new hell forge round(50/6) = 8... and 8 is still greater then 6... but for items with less stats each stat would get an even bigger bonus...

However, in the reality of things later on +50 to all items is not going to be worth it later on... I was always thinking HCS should go back to the % system but nerf the %... however... now that I think of it... HCS came up with the perfect answer to a system that keeps the level of the player in mind, applying a bonus, without using %s...

This is by using the following formula:
Level 1 Forge Bonus = 5 + 1 * round_down(level/50)
Level 2 Forge Bonus = 10 + 2 * round_down(level/50)
Level 1 Forge Bonus = 15 + 3 * round_down(level/50)
Level 1 Forge Bonus = 25 + 4 * round_down(level/50)
Level 1 Forge Bonus = 50 + 5 * round_down(level/50)

Here is a working example of how the new hellforge would work.

Demo HellForge Calculator
Item Level:
Level 1 Forge Bonus:
Level 2 Forge Bonus:
Level 3 Forge Bonus:
Level 4 Forge Bonus:
Level 5 Forge Bonus: