No sweat, here’s the lowdown.
When you get a Nether Orb, it has Gem Slots and Activation Slots, dig? Like so:
Maximum Gems Allowed: 20
Activation Slots: 6
Now, the process starts at Gems. You can make Gems for any creature you’ve summoned, and their purpose is to be shoved into a Nether Orb to make a boosted version of that monster. An Orb can only make one monster, so all the gems have to be for the same creature.
Each gem gives a certain number to the stat you enchant it for based on its level - like a level 5 Ruby might give 50 health, or a level 10, one hundred. So make gems for the stats you want your creature to have bonuses in - an attacker should have Emeralds (which give attack) and Topazes (which give speed and luck), while a tank would probably rather have Rubies (maximum health) and Sapphires (defense). You don’t have to max out the Orb’s gem allowance, but it is a good idea.
Gems can be leveled up by finding Magic Boxes in the Realms (they’re everywhere, trust me), by subquests for the Gem Enchanter, by a specific result from the Pandemonium Token, or by combining two gems of the same level and type, which produces a new gem one level higher.
Diamonds give bonuses to EXP, and they’re of debated usefulness, but I would personally advise you make at least two or three for any Nether, because all Nether creatures naturally level slower than normal creatures, and you don’t want them to fall behind.
Activations on your orb apply multipliers to the bonuses your gems would give you. One activation of each particular enchant type is required to prime it for use - if you have no Ruby activations, then any Ruby gems you’ve enchanted will have no effect at all. It looks like this:
Activations -------------- Multiplier
0 ---------------- 0
1 ---------------- 1
2 ---------------- 2
3 ---------------- 2.5
As you can see, no Activations of an enchant means no bonus in that stat, one allows you to get the Gem bonuses you’ve collected, and each Activation after that just applies a higher multiplier. There are diminishing returns as you go higher, so I’d never go above 3, and that only on rare occasions. So here’s your rule of thumb: first, put one Activation into each stat you’ve got Gems for, and then put the rest of the activations into what you want. Following above, if you had:
3 Diamonds (experience)
3 Rubies (health)
7 Emeralds (attack)
7 Topazes (speed/luck)
0 Sapphires (defense)
Then you’d put one Activation into Diamond, Ruby, Emerald, and Topaz, then go back and put a second point into Emerald and Topaz to make those large groups of gems really matter. You wouldn’t put any Activations into Sapphire, because you don’t have any gems to Activate anyways! The result would be a very fast and strong creature, with more health than average, but the same defense as any other creature of its species. Perfect for an attacker.
You might have noticed that Orbs themselves have colours. They offer further multipliers to your Gems, so if you had a Green Orb (which boosts Emeralds), your creature would get even more attack, at the price of Diamonds giving you less experience (because it gives a malus to Diamonds). All Orbs will have one enchant that’s better and one that’s worse, so pick what suits your needs.
Further, there are Imbued Nether Orbs somewhere deep in the Realms, but I really have to admit that I’ve never seen one and don’t have a damn clue what they do differently.
Once you’ve got all your Gems and Activations ready, go find a Nether Egg crafter in the Realms. He’ll take your Orb and Gems, then fuse them together into an Egg. You’ll take this Egg to your Hatchery (a castle upgrade), and then do a long damn ritual to get it to hatch. At the end of it, though, you’ll have a creature that’s both considerably stronger than normal and more resistant to various status effects. It’s worthwhile, I promise you.