This book includes spells from many sources, including Dragon magazine, web articles previously published on the Wizards of the Coast website, and supplements such as Complete Arcane and Manual of the Planes. Most of the spells are presented with little change, but some material has been revised to v.3.5 based on feedback from thousands of D&D players comparing and debating the strengths and weaknesses of spells at gaming conventions, on message boards, on email lists, and over the counters of their friendly local gaming stores. We hope you like the changes we made to some of these spells.
If you have been playing with a spell we’ve picked up and revised for this book, you should strongly consider updating your character or campaign to the new version. The simplest way to do this is simply offer a “mulligan” to any character who needs tweaking. It’s pretty easy to note that a spell has a different duration or that another class can now cast the spell.
Most of the changes we made to previously published material we made to create an improved version of that material—to help out spells that were formerly suboptimal choices, to adjust spells that were simply too good, or take whatever steps the D&D 3.5 revision made necessary. Of course, if you’re playing with older material and it’s working fine in your game, you shouldn’t feel compelled to change. It’s your game, after all.
(Spell Compendium, pg. 4, emphasis mine)
This is consistent with the general rule in 3.5e that in the case of reprintings,1 the latest printing “wins,” though if a later publication included verbatim the Complete Divine version of energy vortex, I would probably ignore it in favor of the Spell Compendium version—it would be clear to me that the reprint copying Complete Divine was a straight copy and paste, while the Spell Compendium update was a considered thing.
- In cases where a game element hasn’t been reprinted, but is merely referenced, used, or discussed, the opposite is true—the original, “primary” source wins. This is discussed in the introduction to each 3.5e errata file. So, for example, if instead of Spell Compendium reprinting energy vortex as a 3rd-level spell, we had some other supplement describing a 5th-level cleric NPC casting energy vortex, we would treat that as an error, as the primary source would still be Complete Divine and that says energy vortex is a 4th-level spell (likewise, Player’s Handbook is the primary source on the cleric class, and says a 5th-level one cannot cast a 4th-level spell).