Is this spell / object interaction as infinite (and potentially deadly) as I think?

The Spell of Destruction Sphere, Sphere of Destruction, level 12, requires 30 Zeons to cast, for a damage effect of 30 bases (+5 per added effect).

The Prometheum Exxet introduces an effect, Power Boost, which "increases the number of Zeon points feeding the wearer's spells (the amount shown is added to the total Zeon, at no cost to the character)".

If I have an object with Power Boost 30 or 40 (which exists and is strangely accessible in my party …), can I then "infinitely" (provided that I do not fumble my magic projection roll, etc.), cast Sphere of Destruction (or, in fact, any number of spells with a cost of 40 or less)?

Also, in the case of Sphere of Destruction in particular, is it as effective in combat as I think (especially with the 40 Zeon variant)?

The wording of the Power Boost bonus is reproduced below.

Zeon + X: The amount of Zeon added to the spell when the wearer throws it. For example, a spell that normally costs 50 Zeon points to cast would only cost the caster 30 points, if used with an item with a bonus of +20 Zeon. This power does not work for High Magic or Divine Magic spells.