Even lv 20 caster's can run out of spells, Send them to HELL. There are sooooo many challenges, I dont even have to rack my brain to get at least 10.
Netheril was almost dismantled by the Phaerimm, and your talking about a nation of very powerful wizards.
Yes, trying to translate some lv 20+ spells to a computer game would be tough, you just dont use those spells.
I just want my Lv 17 assassin ability
Death StrikeStarting at 17th level, you become a master of instant death. When you attack and hit a creature that is surprised, it must make a Constitution saving throw (DC 8 + your Dexterity modifier + your proficiency bonus). On a failed save, double the damage of your attack against the creature.