So, you're trying to figure out the spell level and version of a creature's spell-like ability. Here is the information you may have been seeking!
Determining a Spell Level for a Spell-Like Ability
It's often necessary to determine what level spell a spell-like ability duplicates. For example, you'll need to know the spell level whenever someone uses a detect magic spell to study a spell-like ability's ongoing effects. Also, as noted earlier, you'll often need to know the ability's level to determine the DC for any Concentration check the user might have to make when employing the ability.
The spell level also affects the saving throw DC for the spell-like ability, but that information usually is included in the user's creature description.
Exactly what level spell a spell-like ability duplicates often proves unclear, because most spells become available to casters of different classes at different levels. To determine the spell level for a spell-like ability, always use the level for the sorcerer/wizard version of the spell. If the spell has no sorcerer/wizard level, use cleric, druid, bard, paladin, or ranger level, in that order. Sometimes a creature's description will specify a kind of caster for the creature's spell-like abilities. If this is so, use the appropriate level for the spell-like ability.
You also can calculate a spell-like ability's level from the saving throw listed for it. Simply subtract 10 + the user's Charisma modifier from the listed DC and the result is the ability's spell level.
As noted earlier, some spell-like abilities don't duplicate spells. For example, a paladin's ability to call a special mount is a spell-like ability gained at 5th level. This ability is very similar to the 1st-level mount spell and can be treated as a 1st-level effect.
Determining the Version of a Spell
Some spells work differently for different kinds of casters. In such cases, use the sorcerer/wizard version of the spell. If the spell has no sorcerer/wizard version, use cleric, druid, bard, paladin, or ranger level, in that order. Sometimes a creature's description will specify a kind of caster for the creature's spell-like abilities. If this is so, use the version for the spell-like ability.
Coming in Part Four of All About Spell-Like Abilities
Skip discusses how you use a spell-like ability, conditions that can affect using a spell-like ability, and the frequency with which a creature can use a spell-like ability.
About the Author
Skip Williams keeps busy with freelance projects for several different game companies and has been the Sage of Dragon Magazine since 1986. Skip is a co-designer of the D&D 3rd Edition game and the chief architect of the Monster Manual. When not devising swift and cruel deaths for player characters, Skip putters in his kitchen or garden (his borscht gets rave reviews).