Summon Swarm and Line-of-sight

[Zathraas]

My warlock is standing 30’ from the intersection of several hallways. Through scouting, the warlock knows that there is a hobgoblin guarding a door down the left hand hallway, but he cannot see the hobgoblin from his current position. He summons a swarm of bats so they are just at the beginning of the left hand hallway, and that lands the swarm within 15’ of the hobgoblin. Since they attack the closest creature they see the hobgoblin and off they go after him, out of the warlock’s sight.

QUESTION: the swarm stays in existence as long as the warlock concentrates, but is there any issue when suddenly the he is out of line-of-sight with the swarm?

He does not have control of the swarm any ways so I would not think he would need to see it just to concentrate on the spell.

 

[Infiniti2000]

The rules do not specify what is required to maintain concentration in regards to line of effect or line of sight.

Concentration

The spell lasts as long as you concentrate on it. Concentrating to maintain a spell is a standard action that does not provoke attacks of opportunity. Anything that could break your concentration when casting a spell can also break your concentration while you’re maintaining one, causing the spell to end.

You can’t cast a spell while concentrating on another one. Sometimes a spell lasts for a short time after you cease concentrating.

I, however, would rule that line of effect (not line of sight as you propose) is required for concentration. Also, note that the swarm stays for 2 rounds after concentration. The spell doesn't suck that bad, though it does suck IMO.

 

[Zathraas]

The regular spell does last for an extra two rounds but the warlock invocation ends the moment concentration ends.

Yes, it does seem like a grey area. This has not come up in our game yet but it occurred to me that my warlock might want to take advantage of the uncontrolled swarm and I always prefer dealing with any of these grey areas before the game is actually going. Line of effect makes sense.

I will have to look around and see if there are other Duration: Concentration spells that give insight into the concept.

 

[kjenks]

If you're looking for a way to control a swarm, consider Dancing Lights. It's an evocation, not an illusion, and an unintelligent swarm may be attracted to the "will o' wisp" or "vaguely humanoid" creatures. If one spellcaster concentrates on the Summon Swarm and the other concentrates on the Dancing Lights, all sorts of fun could ensue.

Or, since no concentration is required to move the Dancing Lights, the same character could do both, casting Dancing Lights first.

 

[MarkB]

Also, note that the swarm stays for 2 rounds after concentration. The spell doesn't suck that bad, though it does suck IMO.

Actually, the 'concentration + 2 rounds' aspect is frequently a downside of the spell, since you don't have control of the swarm and can't immediately dismiss it if it happens to go for the wrong target. The warlock version is generally superior in this regard, given that a warlock can always just summon another swarm if he ceases concentrating too soon.

Personally, I wouldn't consider concentration upon a spell to require line of sight or line of effect. So long as the warlock is still putting in the effort, the swarm should continue doing its thing.

 

[Vegepygmy]

Personally, I wouldn't consider concentration upon a spell to require line of sight or line of effect.

Neither would I.

 

[Infiniti2000]

Well, even a Project Image spells requires line of effect. But, if it doesn't require line of effect for, say, a major image, what does "within the range" mean? With line of effect no longer a factor for concentration, it still is when you place the spell. For example, moving a major image around a corner. You can't move it around the corner directly because that violates the spell placement, but you can move around a corner while maintaining the concentration. That's weird. It also makes it really weird when you try to calculate the range through a planar gate. Being on another plane breaks line of effect (right?), but what does that add in feet to the range of the spell?