Grut's sickle

How many additional power dice is Gruts sickle?

In other words, how many additional power dice per turn would you need to replace Grut's sickle?

On each cast Gruts give about half a power dice of boost. (Fuzzy math : average dice gives you a 3.5, 2 is about half of 3.5, yeah?). So throwing 4 spells gets about 2 bonus dice worth of oomph.

Now, its not quite as powerful as throwing more dice - more dice is a bigger chance of IF. It does mean you can machine gun smaller spells to bleed dice away effectively though