There are some oddities too, like Gate Cleaver + Wall shaker not stacking (just giving the gate cleaver bonus).
Best effect for (non-arti) penetration would be rune smasher [w2f2], void eye [s1] and spell focus [s1] (or RoS/RoW instead of focus if you need +paths), combining to total +5pen.
Best effect for (non-arti) penetration would be rune smasher [w2f2], void eye [s1] and spell focus [s1] (or RoS/RoW instead of focus if you need +paths), combining to total +5pen.
Note - this is for humanoid mage only. 4-armed figures generally have just 1 misc slot and some Pretenders and (iirc) others have more than 2 of them. Master Lich or Crone can have penetration +6/+7 not considering level boost.
On a related note: what spells work best when penetration boosted? Does penetration apply only to spells that must pass a MR check or also to common damage-dealing spells? Consider I'm playing LA Atlantis, so I can cast most mid-research water/death stuff like Falling Frost, Shadow blast etc.