After two and a half years, my D&D 4e campaign is coming to an end. The party reunited a split world, pushed back an evil empire, weaponized a demon plague, and are now prepared to reach Allabar's surface to destroy him once and for all. However, I am not a fan of Epic Tier shenanigans and will never be able to outwit/rules-lawyer the party. What are some ways that I can do this campaign justice, preferably without resorting to mass amount of fake difficulty?
The party in question and the things I notice about them are such…
Pay-may: Gnome Illusionist who's MO is to stun/daze/flat-out-restrict-actions and force failures on saving throw effects.
Jasper: Tiefling Wizard who is the most interested in things being interesting rather than easy. Has a variety of effects at his disposal.
Dmok: Goliath Barbarian, living buzzsaw with supremely high damage numbers. Most of the party's buffs are centered on giving him more attacks or forcing crits.
Adran: H-elf Bard, loads and loads of dice/result manipulation. To include forcing crits for the barbarian, has twelve effects that come up with her basic heal.
Fwkwado: Former Goliath WArden who's cursed into becoming a gorilla. Specializes in grappling all the time.
Earthsea: Eladrin Rogue. The least stand-out of the party as the player is primarily there for the company. Would like to be ranged.
Thanks for the suggestions.