Magery may be the single most powerful skill there is, with 64 different spells available. Many players select magery as the skill they base all of their gameplay on. Higher magery skill expands the number of spells you can cast, increases spell damage, and increases the effectiveness of some skills such as poison and paralyze.
If you are a dedicated Paladin, you may consider training Magery only up to 69.9. When your magery skill is below 70, your faster casting cap for chivalry spells is capped at 4; however if your magery skill is 70 or higher, chivalry faster casting is capped at 2. Of course, this is not a concern if you don't use faster casting with chivalry.
The auxiliary skills to Magery are Evaluating Intelligence and Inscription. Both of those skills affect the effectiveness of almost all of the damaging spells. Your evaluating intelligence skill will go up as you train both magery and magic resistance. See the section on inscription to learn how to train it, and read about the other uses for that skill.
To use magery spells you usually need two things: a magery spellbook with the spell you want to cast, and reagents for the spell. If your spellbook does not have the spell you want to cast, you can add the spell by finding the scroll for the spell and dropping it into your spellbook. Most players have a full spellbook with them at all times. A full spellbook has 64 spells in it, and can often be purchased from other players or from their vendors in the vendor mall. Spellbooks can be created using the inscription skill.
Spells can also be cast using scrolls instead of spellbooks. When casting from a scroll, no reagents are consumed as the reagents are already used in the creation of the scroll. Casting from a scroll can only be done once as it consumes the scroll. One advantage to casting by scroll is that there is a lower skill requirement; casting by scroll reduces the effective spell circle by 2, so an 8th circle spell such as energy vortex can be cast by scroll as easily as a 6th circle spell, which is helpful if you do not have high magery skill.
Players who use magery often will almost always wear jewelry with the properties "faster casting" and "faster cast recovery" (fc and fcr). When wearing gear with a total of 4 fc and 8 fcr, spells can be cast in sequence quite rapidly, and magery becomes a formidable weapon, especially in PVP situations. Note that cast speed on ABCUO is slightly different from other shards; read the details in the combat page of the player guide.
Details about each specific spell can be found here.
Additional notes about magery that may be different from other shards:
The Summon Creature spell always summons a mountable creature - very useful if you don't have an ethereal mount.
Blade Spirits on ABCUO are old style; one follower slot with 80hp, 100 wrestling, and low dispel resistance.
Energy Vortices are new style; two follower slots with 140hp, 120 wrestling, and high dispel resistance.
Paralyze has a minimum paralysis duration of one second.
Magic Reflection will only reflect one spell before the reflection pool wears off, but there is no cooldown period before replenishing the pool. At 100 inscription skill, physical resistance is reduced by 20. Physical resistance cap is reduced by 5.
If you have a faster casting of 4, mana cost for each spell is increased by 1 point.
Note that if you have 100 inscription skill, you should cast magic reflection and reactive armor to give you a free bonus +5 in each elemental resistance.
When training magery, it is quite popular to wear lower reagent cost armor to avoid the consumption of reagents, however this is certainly not a necessity. It is also very helpful to use the necromancy spells lich form and summon familiar to provide more mana, as well as wearing armor with lower mana cost. Jewelry with fc and fcr can also help.
However the most important piece of equipment when training magery is a weapon with the "mage weapon" property, preferably a weapon with spell channeling. When such a weapon is equipped, your effective magery skill is reduced. This might sound like a bad thing at first, but for training it is incredibly useful. For example if your weapon is "mage weapon -25", and you have 30 magery, your effective magery becomes 5. At a skill level of 5 you can train by casting second circle spells, whereas a skill level of 30 you must use third or fourth circle spells. Second circle spells cast faster and use less mana, so this is speeds up training quite a bit. Eventually when training with this weapon, when you get your skill to 75, just take the weapon off and your skill will be 100.
To train the magery skill, cast spells that you have a slight chance of success but will most likely fail to cast. When you fail to cast, no mana or reagents are consumed, but you still have a chance of gaining skill. All spells in a given spell circle have an equal rate of failure, so the particular spell you choose will depend on your methods. For example if you're not using lower reagent cost armor, you may want to cast the spells that consume the fewest reagents. If you're training the healing skill at the same time, you may want to cast damaging spells on yourself so you can bandage yourself as you go.
0-10: Second Circle: Harm, Cure
10-25: Third Circle: Poison, Bless
25-39: Fourth Circle: Lightning, Curse
39-53: Fifth Circle: Mind Blast, Magic Reflection
53-68: Sixth Circle: Energy Bolt, Invisibility
68-82: Seventh Circle: Flamestrike, Gate Travel
82-120: Eighth Circle: Earthquake