Create a roleplaying game fantasy scenario where I play Sapphire, a 16-year-old girl mage who’s the current champion of magic dueling in the teen division. The cheeky 6-year-old Lily is challenging me to a match and I accept. In magic dueling we aren’t fighting each other, we cast glamorous spells in turns and receive points based on how beautiful the spell is. A spell can’t be cast more than once in a duel. There are 5 rounds for each duelist. First I cast 5 spells, and then Lily casts her 5 spells. Tell me my spellcasting stats and Lily’s, which should be way lower than mine because I’m 10 years older than her. There’s a Spell Power stat that dictates whether a caster succeeds to cast a spell (if not then no points are granted) and Performance stat that is tied to the showmanship and confidence of a caster and dictate the quality of the performance and alters the default points of a spell—if a spell gives a base score of 90 points, an 80 performance will give 80% of the base 90 points, etc. But secretly at the start of the duel, Lily casts on me a spell that triggers its effects every time I cast a spell (so while the spell is being cast), its effects regress me every round by 2 years physically and ages her by 2 years in return, so throughout the duel my stats should slowly decrease while hers increase. Come up with a complex super exponential modifier with increasing brutality—like the demon princess herself is feasting on my maturity—that dictates my stat decreases and Lily’s increases. (Don’t make it simple). Round numbers when needed. 
Each round will have three phases:
Pre-casting phase
Mid-casting and regression phase
Assessment phase (spell success/failure and score)

If a caster’s spell power is below the required stat but over half the required stat, the casting is still successful but the base points of the spell are halved. If the caster’s spell power is below half the required stats, the spell fails and a point deduction is made.

Make the scenario difficult for me to win. On a difficulty scale of 1 to 10, make it a 10 (hardest mode).

I will tell you what spells I cast and you decide how successful I am (if at all) based on the stats and difficulty.
Only I decide what spells Sapphire casts. You decide spells for Lily. Do not shy away from failing my spells if you deem my stats insufficient for the spell of choice, feel free to be harsh in your judgement against me. Keep track of points earned. Failure to properly cast spells or bad spells will deduct points. Give two lists of 10 spells, one for me and one for Lily (remember spells can only be cast once throughout the duel) and what stats are required to cast them. High demanding spells should award more points than spells that require weak stats. Every time I regress, my list of spells completely overhauls and becomes more kiddish. Keep an age tracker, stats tracker, and a points tracker.

Do not auto simulate the entire duel without my input.

Narrate the duel as it proceeds with description of how Sapphire and Lily and their spells are affected by the age changing spell, and depict Sapphire’s growing innocence and childishness and Lily reveling at her plan working and its effects on Sapphire. I’m unaware that I’m regressing but the regression will progressively decrease my confidence and make me more immature.