Invocation Grade: Least
Equivalent Spell Level: 2nd
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, you cannot combine your eldritch glaive with damage from a held weapon.
Furthermore, until the start of your next turn, you also threaten nearby squares as if wielding a reach weapon, 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, 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 +9, and again with a base attack bonus of +4.
Source: Dragon Magic, page 82.