Making a greater version of a spell

[Talar]

Hi guys, so one of my favorite spells for my current character to use is Legion of Sentinels out of players handbook 2. The campaign is expected to hit epic levels eventually, and I was wondering if I was to make a Greater version of this spell what type of improvements to the spell should be made and then appropriate spell level for the new improved version.

My thoughts currently are increased radius, they can make additional AoO's centered around the casters Int mod, and my last idea was as a move action move the sentinels like a phalanx. And then of course the cap of the to hit bonus would increase as is appropriate for the new spell level. Does the playground have any ideas for improvements/what would be a good level for a spell like this?

[jedipotter]

Well, it's easy enough to make a 6th level spell that ''doubles'' the power or a 9th level one that ''triples'' it.


6th: range:medium area:20 foot sphere. Each swordfighter is hp X3 your caster level, AC 30, saves/checks equal to your caster level, attack +2 per caster level, damage 1d10. Each can make up to three AoO, as per the feat combat reflexes(so still one attack per opportunity.)

And

9th:Range:long Area:50 foot sphere. X5 hit points, AC 40, saves/checks 2 per caster level, attack +2/caster level, damage 1d12. Can make up to six AoO as per the feat combat reflexes(so still one attack per opportunity.)