It's not "Rouge"... That's makeup.
That'd do it.If you're open to semi-official, look at Zeal Domain from Plane Shift:Amonkhet. It gains the maximize ability of the Tempest domain, except instead of thunder and lightning, it's thunder and fire. Oh, and it gets fireball as a domain spell.
Maximized Fireball will be doing noticeably more damage per spell level than a Maximized Shatter/Call Lightning (48 vs. 32/30 at 3rd, 54 vs. 40 at 4th, 60 vs. 48/50 at 5th, etc.), and over a larger area to boot. And you still have options for Maximized Thunder damage blasting to fall back on if you run into the relatively common Fire Resistance/Immunity.
Perhaps not quite as good as a Tempest Cleric with Call Lightning over a very long adventuring day with several long fights, but those are uncommon. And it's certainly a significant improvement in per-round AoE blasting damage.
Honestly, Tempest is edging towards overpowered as it is (call it "extremely optimal" )... I think Zeal would firmly cross the line into overpowered.