Red equipment fortifications.

In the game, on the X-Legend version, ordinary weapons and armor can be fortified up to +20.
For red-quality armor and weapons, they can be fortified up to level +50.

Here is the interface for a red armor piece fortified to +50.
The stars unlock progressively every 10 fortification levels: the first at +10, the second at +20, the third at +30, the fourth at +40, and the fifth at +50.

Each star gives a stat bonus depending on the equipment or weapon.
Generally, on a red armor set, the first four stars give the same bonus for each piece of the set.
Only the fifth star varies depending on the equipped armor piece.

From +1 to +20

Method 1:

To bring your equipment to +20, you can use the basic method.
with crafting clovers (+7, +10, +13, +15, +16, +17, +18, +19, +20),

There is a type of clover called Prayers for going from +1 to +20; I talk about it a little further below.

as well as weapon scrolls:
Grade A Attack Upgrade Scroll (+1 to +10) for red equipment)
Grade S Attack Upgrade Scroll (+11 to +20) for red equipment)

There are specialized fortification scrolls for going from +1 to +11 and +11 to +20; I talk about them a little further below.

or armor scrolls:
Grade A Defense Upgrade Scroll (+1 to +10) for red equipment)
Grade S Defense Upgrade Scroll (+11 to +20) for red equipment)

How do you access the forge interface?

Method 2:

The second method consists of using no fortification clover at all.
Simply place your equipment and start the fortification.
At first, it will succeed on the first try, but as you increase the fortification level, for example at +8, the success rate will decrease.

The fortification will therefore fail, and you will then need to press the button to repair your equipment.

When fortification fails, a progress bar with a percentage increases, as shown in the picture above.
It increases each time the fortification fails.
When this bar reaches 100%, the current fortification will succeed for sure, but only once.

One last thing: after several failures, the equipment's durability may drop to 0/0, and the equipment will no longer be repairable through the forge interface.
In that case, remove the equipment from the forge and use a Greater Blacksmith's Repair Mallet

From +21 to +50

For this step, normal scrolls will not be enough. There are in-game scrolls dedicated to fortifying red equipment; here they are:

ATK scrolls	Only for weapons
3-Star ATK Awakening Scroll	from +21 to +30
4-Star ATK Awakening Scroll	from +31 to +40
5-Star ATK Awakening Scroll	from +41 to +50

DEF scrolls	Only for armor
3-Star DEF Awakening Scroll	from +21 to +30
4-Star DEF Awakening Scroll	from +31 to +40
5-Star DEF Awakening Scroll	from +41 to +50

Obtainable by killing monsters, and also available at the auction house under the “Scrolls” tab, they are relatively easy to obtain.

There is also a version of these scrolls with a higher success rate:

Legendary ATK scrolls	Only for weapons
1-Star Legendary ATK Awakening Scroll	from +1 to +10
2-Star Legendary ATK Awakening Scroll	from +11 to +20
3-Star Legendary ATK Awakening Scroll	from +21 to +30
4-Star Legendary ATK Awakening Scroll	from +31 to +40
5-Star Legendary ATK Awakening Scroll	from +41 to +50
All Legendary ATK Awakening Scroll	from +1 to +50

Legendary DEF scrolls	Only for weapons
1-Star Legendary DEF Awakening Scroll	from +1 to +10
2-Star Legendary DEF Awakening Scroll	from +11 to +20
3-Star Legendary DEF Awakening Scroll	from +21 to +30
4-Star Legendary DEF Awakening Scroll	from +31 to +40
5-Star Legendary DEF Awakening Scroll	from +41 to +50
Glacial Wings	from +1 to +50

X-star Prayers.

Just like Sprite Blessings used for crafting equipment or weapons, it is possible to make every successful fortification 100% guaranteed, with no risk of failure.
Obtainable through Alchemy and at the auction house, they are generally expensive.

To use them, simply place them in the slot reserved for clovers, at the top right of the forge interface.

Prayers	Only for red armor and weapons
2-Star Sprite King Prayer	from +1 to +20
3-Star Sprite King Prayer	from +21 to +30
4-Star Sprite King Prayer	from +31 to +40
5-Star Sprite King Prayer	from +41 to +50
All Sprite King Prayer	from +1 to +50

Re-enchanting red equipment.

You can obtain enchantments for red equipment and weapons, as shown above.

Sacred re-enchantments
Holy Enchantment Stone II
Holy Enchantment Stone I
Holy Enchantment Stone

Obtainable through alchemy, at the auction house...