Can you purposefully fail a caster level check vs SR?

[ksbsnowowl]

Got an army of Tanarukk marching toward my PC's town.  There are a few casters amongst the tanarukk.  Tanarukk have SR 14.  Can a tanarukk wizard purposefully fail his caster level checks, so as to not hurt his friendlies with SR, but hurt the PC's (for example) who have no such protections?  I'm think along the lines of a fireball laid into the PC/tanarukk battle front.

[Tiltowait]

Yes.

[kitep]

I can't think of any text that says one way or another.

I would rule that a caster can intentionally lower his caster level when casting a spell.  So a 10th level caster would normally cast a fireball as a 10th level caster for a 10d6 fireball, SR check = 10 + 1d20.

But I would allow the caster to cast as a lower level caster as well, such as a 5th level - but it would then only do 5d6, have a range of 400' + 5 * 40', and an SR check = 5 + 1d20.

I would not allow a spell to be cast at a lower level than the minimum to cast it.  Since fireball is a 3rd level spell, it requires a 5th level wizard, so 5 is the lowest he could go.

[Aradu]

The caster level thing is in the actual rules though (and exactly as you describe), not just what you'd allow.

[Jackinthegreen]

There are rules for willingly failing a saving throw, so there's a precedent for failing a d20.  Looking at http://community.wizards.com/go/thread/view/75882/19566842/Choosing_to_fail_a_d20_check:_need_reference&post_num=5, it seems fairly clear that within the RAW, you can't choose to fail a caster level check.

However, as one person in that thread opined, not being able to intentionally fail certain tasks leaves you without certain story situations that could be interesting or useful.

[ksbsnowowl]

So no-go on the auto-fail, but you can voluntarily lower your CL (to the minimum to cast the spell), with resulting lowering of effect.  Good to know.

[kitep]

I would also add that if you have feats that raise your SR you don't have to use them.  So if the wizard has spell penetration which adds +2 to overcome SR, he can choose to not use that feat on his fireball.

[kitep]

I just came across this item:

Ring of Arcane Supremacy (Complete Mage, p126)
Let's you reroll your SR check.  Must accept the results of the second roll, even if lower.
Free action, but not more than once/round.  3x/day.
Price: 12,000gp

Complete Mage page 121 also has a spell called True Casting.  Wizard 1.  Next spell gets +10 insight to overcome SR.  Duration 1 spell - so I guess it could last for days, or even years, if you take your time casting the next spell.  While you don't want a +10, it's not hard to imagine your wizard researching a spell to give a -10.

[Halinn]

I would also add that if you have feats that raise your SR you don't have to use them.  So if the wizard has spell penetration which adds +2 to overcome SR, he can choose to not use that feat on his fireball.

Could you give me a rules quote on that?

[kitep]

Sorry, I can't.  I should have made it it clearer that it was my opinion only.

[zugschef]

Sorry, I can't.  I should have made it it clearer that it was my opinion only.

raw you can't.