Seige spell (3.5)

[Lightlawbliss]

So I am considering giveing my players a spell and want to get the playground opinions on it before I potentially break the game. For now let's ignore the actual composition of the party and focus on the spell.

Siege Blast
conjuration (creation)
sor/wiz 4
V,S
casting: 1 round
Medium Range
Area: see text
concentration (max round/lvl)
ref/partial

This spell initially creates a 1' diameter orb of contained concentrated force. Every round for the spells duration, you may move the orb 5' or increase the orbs diameter by 1'. The spell ends if the orb touches anything or vise verse. A concentration check (DC 20+ orbs diameter in feet [not sure on DC yet])

Upon the spells termination by any cause, the contained force is released, damaging the surroundings. The squares adjacent to the orb (the first squares not completely contained by the orb) take 1d8 force damage per 4 caster levels plus 1d8 force damage per additional foot of the orbs diameter. Every 5 feet further out takes 1 die less damage until no damage is done. Something in multiple cubes takes damage for each cube it occupies. A successful reflex save minimizes the damage (each die does only 1 damage).

Following the damage, everything affected is hit by a bull rush attempt directly away from the orb with total equal to damage received. This bull rush automatically follows you.


My main questions are as follows:
Is it ever worth preparing? why or why not.
Is it to good? why or why not.
any recommended changes? please provide reason(s) to do your recommendation.
any meta-magic I may want to watch out for? why?

[PairO'Dice Lost]

Is it ever worth preparing? why or why not.

I'd say no, unfortunately. It deals 1d8 damage per round of concentration, and you can only concentrate for 1 round/level, so this is basically a roundabout way of dealing [CL]d8 damage in a [5*CL]-foot radius (but not even that much, because the damage falls off based on distance). d8s are nice, force damage is nice, and the area is nice, but the time investment is too much.

As is the orb vulnerability: if it explodes as soon as anything touches it, in a siege situation anyone who noticed the orb would just have an archer or two target the orb and blow it up while it was still small, and while you'd certainly get some damage out of each orb that way it's less damage than just casting fireballs at the wall.

Compare this to the channeled pyroburst spell (PHB2). It's also a 4th level wizard spell that deals more damage with concentration at Medium range, but it only requires 1 full-round action to deal [CL]d8 damage in a 15-foot radius, and you can concentrate for 1 more round to increase that to [CL]d10 damage in a 20-foot radius. Generally, spells dealing force damage drop their die type by 1 size to compensate, so a channeled forceburst that topped out at d10s for 2 rounds of concentration would seem appropriate.

There is one problematic part of the spell, though: the bull rush at the end where the bull rush bonus is equal to the damage received. It's problematic because (A) no other effect in the game works like that, and even at the minimum caster level that could send them flying 50+ feet if they're at the center of the blast, and (B) that requires calculating a different bull rush modifier for every single creature caught in the blast after already calculating different damage totals for each creature caught in the blast, which is very time-consuming and not really worth it.

Here's how I'd suggest changing the spell to address those issues:

Siege Blast
Conjuration (Creation)
Level: Sor/Wiz 4
Components: V,S
Casting Time: 1 round
Range: Medium
Area: See text
Duration: Concentration, to a maximum of 1 round/2 levels
Saving Throw: Reflex partial
Spell Resistance: Yes

This spell initially creates a 1' diameter orb of contained concentrated force. Every round for the spells duration, you may move the orb 5' or increase the orb's diameter by 1'. The spell ends if the orb touches anything or vice versa, but you may attempt to stop the orb from detonating with a Concentration check (DC 20 + 2*diameter of the orb) if someone or something else attempts to detonate it before you wish to do so.

Upon the spell's termination, the contained force is released, damaging the surroundings. All creatures and objects adjacent to the orb take 1d8 force damage per 2 levels, plus 1d8 damage per foot of the orb's diameter. Creatures and objects 5 feet further out takes 1 fewer die of damage than adjacent objects and creatures, creatures and objects 10 feet further out take 2 fewer dice of damage, and so on until no damage is done. Following the damage, every affected creature is hit by a bull rush attempt directly away from the orb; treat the explosion as having a bull rush modifier equal to the number of dice of damage the creature took.

A successful reflex save minimizes the damage (each die does only 1 damage) and negates the bull rush effect.

[Lightlawbliss]

I like the concentration and initial damage.

will have to think about the bull rush some more. The launching stuff (like a wall) was kinda the idea, but I can see how I may have gone to far.

[PairO'Dice Lost]

The launching stuff (like a wall) was kinda the idea, but I can see how I may have gone to far.

As I said, the "launching people explosively" part isn't problematic in and of itself, the issues are the unreliability (you could launch a particular creature or object anywhere between 1 and 60 feet based on the damage roll and the bull rush roll) and the fiddliness (calculating a different modifier for, and then rolling for, every single square in the area) of doing it in that particular manner.

You could always change it to something closer to Explosive Spell rather than using bull rush rules: everything gets pushed X feet if they fail their save, taking Yd6 feet per 10 feet moved if they're pushed into another object. That would get the idea across in a much simpler way.

[Lightlawbliss]

dice: I wouldn't do the save negate you are describing in the second part, I feel that is going to far considering the effective cast time.

part of me is considering just making it set damage instead of dice. Another part of me is thinking about "everything in a band takes the same damage" and just having the player roll the dice once and dice "fall off" as you go out.

[PairO'Dice Lost]

dice: I wouldn't do the save negate you are describing in the second part, I feel that is going to far considering the effective cast time.

Point. Perhaps make the save for half damage and half the bull rush modifier.


part of me is considering just making it set damage instead of dice. Another part of me is thinking about "everything in a band takes the same damage" and just having the player roll the dice once and dice "fall off" as you go out.

Just rolling the dice once would definitely be a good idea.

[Lightlawbliss]

Point. Perhaps make the save for half damage and half the bull rush modifier.

The half damage is a possibility. Half the bull rush modifier would definitely do a lot if it does to much and renders the spell not worth the cost is the question.