When to use Magus Roll?

[Apollyonzorz]

From discussions with current endgame COR's i've surmized that Magus roll is pretty much useless outside a select few HNM / Gods. Which HNM's is Magus roll best implemented?

I witnessed its effectivness in the fight with the Limbus Ultima, but are there only a select few or is it a safe roll to use for just about all HNM's?

 

[Aura]

I plan to eventually test this on the Zhayolm Remnants boss. He uses a move which is more or less equivalent to 4,400 Needles, with one small difference that we recently discovered: Shell negates the damage, which is not the same for standard Needles attacks. So it makes me question whether or not Magic Defense Bonus will work as well. Not sure when we're going back there to test it, but it's on my list of potential uses.