The first ability a warlock learns is eldritch blast. A warlock attacks his foes with eldritch power; using baleful magical energy to deal damage and sometimes impart other debilitating effects.
An eldritch blast is a ray with a range of 60 feet. It is a ranged touch attack that affects a single target; allowing no saving throw. An eldritch blast deals 1d6 points of damage at 1st level and increases in power as the warlock rises in level. An eldritch blast is the equivalent of a 1st-level spell. If you apply a blast shape or eldritch essence invocation to your eldritch blast (see page 130); your eldritch blast uses the level equivalent of the shape or essence.
An eldritch blast is subject to spell resistance; although the Spell Penetration feat and other effects that improve caster level checks to overcome spell resistance also apply to eldritch blast. An eldritch blast deals half damage to objects. Metamagic feats cannot improve a warlock's eldritch blast (because it is a spell-like ability; not a spell). However; the feat Ability Focus (eldritch blast) increases the DC for all saving throws (if any) associated with a warlock's eldritch blast by 2. See page 303 of the Monster Manual.
This eldritch essence invocation allows you to change your eldritch blast into a frightful blast. Any creature struck by a frightful blast must succeed on a Will save or become shaken for 1 minute. A shaken creature struck by a frightful blast is not affected by the shaken aspect of the blast but takes damage normally. Creatures with immunity to mind-affecting spells and abilities or fear effects cannot be shaken by a frightful blast.
Your eldritch blast takes on physical substance; appearing similar to a glaive.
As a full-round action; you can make a single melee touch attack as if wielding a reach weapon. If you hit your target is affected as if struck by your eldritch blast (including any eldritch essence applied to the blast). Unlike hideous blow (Complete Arcane 134); you cannot combine your eldritch glaive with damage from a held weapon.
Furthermore; until the start of your next turn; you also threaten; and you can make attacks of opportunity with your eldritch glaive. These are melee touch attacks.
If your base attack bonus is +6 or higher nearby squares as if wielding a reach weapon you can (as part of the full-round action) make as many attacks with your eldritch glaive as your base attack bonus allows.
For example; a 12th-level warlock could attack twice; once with a base attack bonus of+6; and again with a base attack bonus of +1.
When you use this invocation; you can activate great powers of vision; allowing you to see invisible creatures and objects (as see invisibility). You also gain darkvision out to 60 feet for a period of 24 hours.
You detect magical auras. The amount of information revealed depends on how long you study a particular area or subject.
1st Round: Presence or absence of magical auras.
2nd Round: Number of different magical auras and the power of the most potent aura.
3rd Round: The strength and location of each aura. If the items or creatures bearing the auras are in line of sight; you can make Spellcraft skill checks to determine the school of magic involved in each. (Make one check per aura; DC 15 + spell level; or 15 + half caster level for a nonspell effect.)
Magical areas; multiple types of magic; or strong local magical emanations may distort or conceal weaker auras.
Aura Strength: An aura power depends on a spell functioning spell level or an item caster level. If an aura falls into more than one category; detect magic indicates the stronger of the two.
Functioning spell (spell level): Faint (3rd or lower); Moderate (4th-6th); Strong (7th-9th); Overwhelming (10th + deity level)
Magic Item (caster level): Faint (5th or lower); 6th-11th (Moderate) 12th-20th (Strong) 21st (artifact).
Lingering Aura: A magical aura lingers after its original source
dissipates (in the case of a spell) or is destroyed (in the case of a magic item). If detect magic is cast and directed at such a location; the spell indicates an aura strength of dim (even weaker than a faint aura). How long the aura lingers at this dim level depends on its original power: Faint (1d6 rounds); Moderate (1d6 minutes; Strong (1d6*10 minutes); Overwhelming (1d6 days).
Outsiders and elementals are not magical in themselves; but if they are summoned; the conjuration spell registers.
Each round; you can turn to detect magic in a new area. The spell can penetrate barriers; but 1 foot of stone; 1 inch of common metal; a thin sheet of lead; or 3 feet of wood or dirt blocks it.
Detect magic can be made permanent with a permanency spell.