When you start stacking on other reducers it lets you keep low level spells low level even when pimped out.
Arcane Thesis+Incantrix capstone would be very standard, nothing 3rd party or potentially abusive. Just a straight up strong wizard build. No dm would have grounds to say "no" based on questionable rules interpretations or anything.
Empower, Enlarge, Fel Weaken, Transdimensional, Enervate, Fel Drain, Split Ray, Chain Spell (easy metamagic to reduce by another 1)maximize (easy metamagic) Ray of Stupidity.
1d4+1 int damage, with an extra 50%, Extra range, a-4 str tacked on, full effect vs incorporeal/ethereal, extra 50% damage vs living creatures, living creatures get 1 negative level, 1 ray splits to 2, chain the full effect of both rays to a number of targets equal to your level for half damage, maxing the dice roll.
Easy metamagic reduces the cost on both 3 level feats by one (you have to take easy meta for both of course but as a 15+ character with 10 levels of incantrix you're swimming in metamagic feats). Incantix capstone reduces everything by one. Arcane thesis reduces everything by another 1 level and does not have a minimum, so can reduce the level modification to 0. The effect listed above is a second level spell. 20 points of int damage with no save to your primary target and you've just taken the enemy wizard you're facing off against completely out of the game and 10 points to every other target, along with str penalty and negative level puts a big hamper on his cronies.
As a second level spell.
The above list is just kind of a hodgepodge of 1 to 2 level metamagic, and most players won't likely have that specific list but it illustrates my point. Throw a Quicken Spell (easy metamagic) to make it a 3rd level and cast two of them in the same round for extra retardedness (int damage... retardedness... damn I'm clever!) Or perhaps Twin Spell (easy metamagic) to double the above mess as a 3rd level spell doing 40 int damage to the main target and 20 to everything else. Heck, if that's not enough use that as a third and a quickened twinned as 3rd and 4th level spells. Granted, you're not likely to have *that* many metamagic feats (backpack full of metamagic rods maybe? ;) ) but you can see where arcane thesis becomes the building block for stupid abuse (ray of stupidity strikes again!) of spells. Now, I will grant you that it is underwhelming on a blasting spell, but if you're blasting, you're doing it wrong to start with. (Blasting makes casters more balanced with everyone else of course, but that's a different discussion.)
EDIT:Please note that using 0 level metamagic to reduce other metamagic modifiers is consider bad form and/or against the rules by many. If you do this, your DM has a much better chance of just nixing the whole thing and outlawing the feat. Not passing judgment or saying what is right or wrong, just saying if you do it, be prepared for your dm to rain on your parade by removing it from the game. My example above does NOT use this process and never reduces any single metamagic feat below 0.