So I don't have to type these rules out every time I mention them.
When casting a spell against a creature with Spell Resistance, your caster level is lowered by (SR -10) and the DC by half that. For instance, a CL 7/DC 17 fireball
cast against a creature with SR 14 would become a spell with a caster level of 3 and a DC of 15. The reduction in CL affects duration, etc. as normal. If your caster level becomes 0, the effects of the spell are negated for that creature.
Anything the creature is in physical contact with also benefits from his spell resistance, as long as no part of it is more than 5ft away. If a creature lies partly outside this radius then it gains the benefits only if the creature with SR would provide them with cover against the spell, and parts of a large object (such as a building or the ground) outside the radius are affected as normal.
If your spell would not normally allow SR, halve the target's SR after subtracting 10 (i.e. a SR 16 target would effectively have SR 13).
The Spell Penetration feat allows you to treat your targets' Spell Resistance as 2 points lower.
You may choose to temporarily reduce your Spell Resistance whenever affected by a spell, to a minimum of 0, in order to receive helpful spells from allies; your SR returns to normal immediately afterwards. This is not an action.New FlawSpell Wall
Spell Resistance based on character levelEffect:
You may not choose to lower your Spell Resistance.