Magic Here and Magic There

Spellcasters who are sensitive to the ebb and flow of natural energies can find the best places to effect their summonings. For example, fire energy is strong on certain elemental planes, while the brooding hollows of gray northern fens enhance the necromancer’s efforts. You can further reinforce the magical nature of spell casting in your campaign by emphasizing environmental influences. There are two ways to do this.
In the simplest form, apply a bonus or penalty to spell checks. For example, all turning checks in a cursed graveyard receive a -2 penalty to spell checks while necromantic animations gain a +2 bonus. Ley lines may serve as conduits for magical energies over long distances and have chaotic effects when they cross. Standing stones or hideous primitive altars may produce similar modifiers to pagan magic.
A more exciting approach is to add secondary effects. Let the spell function as normal but with the addition of something special. For example, on the elemental plane of fire, all spells that affect an enemy with magical energy—such as color spray or magic missile—could be subject to the following side effects, according to the spell check. This is just one example; the reader is encouraged to create his own effects.

Check	Side effect
1 - 11	No side effect.
12 - 13	A cloud of ash explodes around the target, coating him in a fine gray mist.
14 - 17	Sparks trace a line from the caster’s fingertips to his target, illuminating the arc in a flash of light.  The sparks are insufficient to cause damage but easily ignited objects (such as paper or dry leaves)  along the path, on the caster, or the target’s person catches fire in a burst of flame.
18 - 19	A burst of red-hot cinders appears around the target. They cause an additional 1 point of burning  damage as they scorch him.
20 - 23	A large pile of red-hot cinders appears around the target. They cause an additional 1d3 points of burning damage as they scorch him.
24 - 27	The target is enveloped in a corona of flame. The flash fire inflicts an additional 1d6 damage and ignites any flammable objects on his person.
28 - 29	The target is enveloped in a massive fireball. It inflicts an additional 2d6 damage and ignites any  flammable objects on his person.
30 - 31	The spell manifests completely as a fire-based effect instead of its normal effect. It inflicts an additional 3d6 damage and the target catches fire, suffering an additional 1d6 damage each round until he makes a DC 10 Reflex save at the start of a round.
32+	The spell manifests completely as a fire-based effect instead of its normal effect. It inflicts an additional 4d6 damage and the target catches fire, suffering an additional 1d6 damage each round until he makes a DC 20 Reflex save at the start of a round.