Death Knell is a harmful spell, you throw it in the Glyph, anytime later any of your clergy can go grab some sacrifice and throw 'em on the altar and boom, you get +1 CL. So, the most efficient way to set up a delayed sacrifice in Pathfinder is definitely Glyph of Warding. If the spell is banned in your game, or functions too differently, this answer won't work. I'm told Death Knell's cumulative bonus is somewhat controversial. Widen spell doesn't help us here, cause the effect isn't the right sort :( If it was, we could spare over one hundred quadrillion people's lives. (in the end, we're gonna end up only needed a 60th those guys because we're going to prestige class into eldrich knight and do the actual casting in a single round instead of 6 hours, but that just decreases our target by 1.5 orders of magnitude, which doesn't affect the calculations much- things will take maybe 6 rounds less time) That sounds like a lot! Let's see how long it would take us to set up this casting.

Assuming you're level 20 and want a spherical realm 1000 miles in diameter (it's a small moon, but it'll do), you 'only' need approximately 400 quadrillion sacrifices (or 400 billiard, if you're British). Each sacrificed creature provides you with +1 CL for 10 minutes per HD. Sacrifice the inhabitants of the Material Planeĭeath Knell (and similar) is the premier method to arbitrarily boost CL at the cost of many, many lives.

Waying spellhunter