Rules-light Combat Magic and Healing Magic. Uses a Mana Pool.

Freeform Casting

Magic is divided into domains and treated like any other skill. A Fire Mage could cast Fireball, or Fire Whip, or any other freeform use of fire that the player could think of, but the character would only be able to cast fire-based spells unless they bought another magic domain. The amount of damage dealt by a spell is defined by the amount of mana spent to produce it.

Basic Casting

Casting a spell against the environment is 4df + caster's skill vs GM-decided difficulty. A successful spell costs mana based on its difficulty. A failed spell still costs mana.

Casting a spell on an opponent is a simple opposed roll: 4dF + caster's skill vs opponent's defense. A successful spell costs mana based on damage, target, and (optionally) distance. A failed spell still costs mana.

Optional rule (Wound track system): A spellcaster may take Hurt damage to reduce the mana cost of a spell by 3 points.

Optional rule (Hit Point system): A spellcaster may take 4 points of damage to reduce the mana cost of a spell by 1 point.

Mana

Mana is an attribute that determines your mana pool (the maximum of mana you can have at a time). Start with 1 mana for Terrible and add 1 mana for each additional level on the Fudge Ladder. So Poor would be 2 mana, Mediocre would be 3, Fair would be 4, etc.

A spellcaster's mana pool and healing dice (see "healing") are automatically restored after 8 hours of rest.

Alternate rule: 1 mana point is regained every 5 combat rounds, and mana completely regenerates in minutes. Healing is still per-day.

Combat spells

The default combat spell has one target, ODF 3 or 2d6 damage, and costs 1 mana. Doing extra damage and/or targeting more than one person increases the mana cost of the spell.

Target
1 target: 0
Group: +2

Damage
ODF: +1 mana to do an additional 3 points of damage
d6: +1 mana to do an additional 2d6 points of damage

Optional Rule:
Ignores mundane defenses (armor, etc.): +2

Optional Rule: distance penalties to skill roll or mana cost
Melee Range: 0
Nearby: 0
Long Range: +1
Very Long Range: +2

Non-combat spells

The player describes what he's attempting and the GM sets a difficulty, which in turn defines the spell's mana cost.

Mana Cost:
Legendary: 4
Superb: 3
Great: 3
Good: 2
Fair: 2
Mediocre: 1
Poor: 1
Terrible: 0

Healing

Maximum per-day uses:
Legendary: 8d6/6 wound levels
Superb: 7d6/5 wound levels
Great: 6d6/4 wound levels
Good: 5d6/3 wound levels
Fair: 4d6/2 wound levels
Mediocre: 3d6 HP/1 wound level
Poor: 2d6 HP/Move lowest wound down 1 (x2)
Terrible: 1d6 HP/Move lowest wound down 1

Your skill level determines the number of healing dice you can roll, or the number of times you can reduce wounds by one level, per day.
Healing doesn't cost any mana.

You don't have to use all your dice or wound levels at once. For example, if you have Mediocre healing (3d6) and you decide to roll 2d6 to cure one player, you could still heal another 1d6 later in the day before running out of juice.

Update:

Upon giving this more thought, it occurs to me that I could replace the mana cost with a penalty to the spell difficulty. So a Fire Mage with Great spellcasting skill could cast a 1d6 fireball at Great, or a 2d6 fireball at Good, or a 3d6 fireball at Fair.

It needs playtesting, but it would be simpler and wouldn't require the mana cost chart for non-combat spellcasting.