From the publisher's website:
Although a vast number of spells are available in the game's core rulebooks, many GMs and players have an insatiable desire for more options. In many cases it's not necessary to create new spell options from scratch, since a few minor changes to an existing spell can create something with a very different feel or impact on game play. These spell variants are based on the idea that you can make a lot of different effects with fairly minor changes to how a spell works, or by combining effects of multiple spells, or by mixing a spell and magic item or even a class ability (preferably from a class not used in the campaign).
Some spell variants are common and fairly obvious, such as having an iceball spell that is a fireball that deals cold damage. The following list of one hundred ten spell variants are slightly more complex and are designed to show how you can create new spells without too much work. One important tip is that when you base a new spell on an old one, many details—such as its school, components, duration, and often even interaction with other spells—is already determined. Similarly, you can often create spells that have entirely new themes just by changing casting time and legal targets. This last trick is often a great way to make spells appropriate for new classes.
For example it's fairly obvious a druid class shouldn't have the haste spell on its spell list, but a new spell called pack tactics that acts like haste but can be cast only on creatures of the animal type is perfect for druids. And even better, you already know it's about a 3rd-level spell, since it doesn't do anything the wizard haste spell doesn't.
Because the following are all variants of existing spells, we present only a minimal sketch of each spell. Any information not presented or mentioned is the same as the base spell the variant is built off. These spell descriptions are so short, it seems silly to list each one multiple times if it happens to appear on more than one class spell list. As a result, each spell variant lists what class and level it is designed for after its name. In cases where the spell appears at different levels for different classes, it is listed with the level of the first class to gain it. Other information such as School, [Descriptor], Casting Time, Components, Range, Area, Targets, Duration, Saving Throw, and Spell Resistance are only given if they differ from the base spell.