Shaper of Worlds
1) No reason to change a Giant's stats or how they work. You have your bonus compared to his. Roll and find out!I'm intrigued. I wonder where it might break things, though.
In combat, you try to grapple a giant. What determines who wins?
You try to feint someone in combat, to get advantage on your attack next round. Do you make a Deception check (modified by Charisma), or is it just a proficiency bonus check?
The Dragonlance mage character Raistlin is renowned for being fragile and sickly, having sacrificed his health for magical power. How do you model this? Instead of having a low Con, does he have some special curse, and in exchange get some nifty magical powers?
Conan (strong) fights Inigo Montoya (nimble). How does this fight mechanically differ from having two Conans fight each other, or two Inigos?
2) Probably Deception for skill use. Which could lead to Inigo being particularly adept at feinting but unskilled in grappling)
3) Feat that allows you to expend your Hit Dice during short rests in exchange for more spell slots.
4) Conan Rages while Inigo Sneak Attacks? Alternatively: Skill Use and Combat Maneuvers in the fight.