There are two main routes you can take to make money by using magic on Runescape. Entering the Player versus Player scene is one, reaping higher rewards to those with the skill and contacts, or enchanting and charging orbs, making you a lesser profit but always ensuring you will have a consistent source of income.
PLAYER VERSUS PLAYER
The way to make money with combat magic is to find a team of other players and enter the area to fight. The money in it is from the items your enemies will drop, though this has been restricted greatly recently, you can still make a nice profit as long as you can stay alive.
To assemble your team you'll need at least four people to compete, at least two hand-to-hand combatants, at least one mage (you), and one archer. The more people you have, the better, as always there is strength in numbers, and you can easily outnumber your foes.
Obviously you are going to need a fairly high magic level relative to your combat level and the levels of your opposition. Know what spells you can and should be casting to deal the most damage to your opponents. The following is a list of all the combat related spells, along with what they do and their rune requirements.
LEVELS 1 20 - These are spells you shouldn't focus on casting in most situations, because they just aren't powerful enough. They are fine to fall back on if you run out of runes, or you just need a quick spell to fall back on and gain advantage.
Level 1 Wind Strike Air Missile 1 Air Rune, 1 Mind Rune
Level 3 Confuse Reduces opponents attack by 5% - 3 Water Runes, 2 Earth, 1 Body
Level 5 Earth Strike Earth Missile 2 Earth Runes, 1 Air Rune, 1 Mind Rune
Level 11 Weaken Reduces opponents strength by 5% - 3 Water, 2 Earth, 1 Body
Level 13 Fire Strike Fire Missile 2 Air Runes, 3 Fire Runes, 1 Mind Rune
Level 17 Wind Bolt Wind Missile 2 Air Runes, 1 Chaos
Level 19 Curse Reduces opponents defense by 5% - 2 Water Runes, 3 Earth, 1 Body
Level 20 Bind Opponent can't move for 5 seconds 3 Earth Runes, 3 Water, 2 Nature
LEVELS 20-40 The power of your spells is reaching a higher level of significance, being able to cast bolts that can hit up to 10+, which makes a huge difference in combat when you've got another teammate hitting the same opponent with arrows, and another in their face attacking by hand.
Level 23 Water Bolt Water Missile (Max hit 10) 2 Air Runes, 2 Water, 1 Chaos
Level 29 Earth Bolt Earth Missile (Max hit 11) 2 Air Runes, 3 Earth, 1 Chaos
Level 35 Fire Bolt Fire Missile (Max hit 12) 3 Air Runes, 4 Fire, 1 Chaos
LEVELS 40-60
Level 41 Wind Blast Wind Missile (Max hit 13) 3 Air Runes, 1 Death
Level 47 Water Blast Water Missile (Max hit 14) 3 Air Runes, 3 Water, 1 Death
Level 53 Earth Blast Earth Missile (Max hit 15) 3 Air Runes, 4 Earth, 1 Death
Level 59 Fire Blast - Fire Missile (Max hit 16) 4 Air Runes, 5 Fire, 1 Death
LEVELS 60++ (Members only Spells)
Level 62 Wind Wave Wind Missile (Max hit 17) 5 Air Runes, 1 Blood
Level 65 Water Wave Water Missile (Max hit 18) 5 Air Runes, 7 Water, 1 Blood
Level 66 Vulnerability Reduces opponents defense by 10% - 5 Earth, 5 Water, 1 Soul
Level 70 Earth Wave Earth Missile (Max hit 19) 5 Air Runes, 7 Earth, 1 Blood
Level 73 Enfeeble Reduces opponents strength by 10% - 5 Earth, 5 Water, 1 Soul
Level 79 Entangle Opponent can't move for 15 seconds 5 Earth, 5 Water, 4 Nature
Level 80 Stun Reduces opponents attack by 10% - 12 Earth Runes, 12 Water, 1 Soul
ENCHANTING
Enchanting is the slow but steady way of making money with magic in Runescape. To cast enchantment spells you just need a piece of jewelry (amulet, bracelet, ring, or necklace) with the appropriate gem based on your level, and the runes to cast the enchantment spell. Then just sell the enchanted jewelry when you're done!
Level 7 - Enchant Level 1 Jewelry (Sapphire) - 1 Water Rune and 1 Cosmic
Level 27 - Enchant Level 2 Jewelry (Emerald) - 3 Air runes, 1 Cosmic.
Level 43- Enchant Level 3 Jewelry (Ruby) - 5 Fire Runes, 1 Cosmic
Level 57, - Enchant Level 4 Jewelry (Diamond) - 10 Earth Runes, 1 Cosmic
The Rest are Members Only Spells:
Level 68 - Enchant Level 5 Jewelry (Dragonstone) 15 Earth Runes, 5 Water, 1 Cosmic
Level 87 Enchant Level 6 Jewelry (Onyx) 20 Earth Runes, 20 Fire, 1 Cosmic
CHARGING ORBS
This is only available to members on Runescape, but it's just like enchanting, only instead you use magic to charge orbs and make magic staffs. All you need to cast these spells is an unpowered orb, the runes to cast the spell, and a battlestaff, and you have to be at the respective obelisk to cast the spell on it. Once the orb is powered, you just use the orb on the battle staff to make it an air, fire, water, or earth battlestaff. Then just sell the battlestaff when you're done!
Level 56 Charge Water Orb (Cast on Water Obelisk) 30 Water Runes, 3 Cosmic, 1 Glass Orb
Level 60 Charge Earth Orb (Cast on Earth Obelisk) 30 Earth Runes, 3 Cosmic, 1 Glass Orb
Level 63 Charge Fire Orb (Cast on Fire Obelisk) 30 Fire Runes, 3 Cosmic, 1 Glass Orb
Level 66 Charge Air Orb (Cast on Air Obelisk) 30 Air Runes, 3 Cosmic, 1 Glass Orb