Build for 2 (gods) Powerful NPC's

[arkangel111]

basically the campaign will have the player's choose which guy is the real bad guy. So I need 2 builds because I don't yet know which they will choose and they don't even realize there is going to be a choice.

i'm expecting the characters to be around level 15-17. There are 6 players in the group.
1 Rogue with lots of mobility options
1 Scout with some battlefield control abilities
1 Barbarian with some minor healing abilities
1 Druid that stays mostly as different forms and forgoes casting entirely
1 Ranger with some utility arrows (she crits almost every hit)
1 Cleric with a strong focus on healing (kind of an NPC most days since the player rarely shows up)

This will be the end fight of the campaign so if player's die fighting it's ok, but I don't want it to be a walk in the park for the bad guy either. The player's are currently seeking the pieces to a magic Item to reduce baddies godlike powers to a beatable level. On top of that the 2 big guys will be fighting each other when the players finally have to decide so they should be weakened down to a manageable level, whichever they choose to help will be out of the fight at that point activating said magic item that will deliver the killing blow.

For rule sets I am thinking they should likely be gestalted characters and assume they have plenty of feats for whatever you wish them to do. We are using a homebrewed system but for arguments sake lets call it 3.P. Since they will be gods, I could care less about banning sources so anything goes, though obscure feats and such I would love to know their source so I can look it up later. They are both winged and have a perfect fly speed. I'm also planning on giving them extra actions like in 5e so they can compete with the action economy, though how many I have yet to decide (ideas welcome). A little about each god to help with build directions.

Telara - HUGE Female deity, Goddess of Light and Magic. She wields a Great sword, and a Shield. She is believed to be the reason magic exists in this world , though her magic seems more divine in nature. Her magic comes from trapped souls that she siphons the energy from. She has built the nation up under the guise of a good guy (girl) and destroyed all references to her and her fellow apprentices (all dead by the time players get here) gaining their powers from Tekhar. In all respects she seems the good guy and has even done amazing works. while her magic stems from evil the players should face a dilemma as to whether or not killing her is truly the right thing to do. keeping her in power will keep the status quo and their world will prosper for it, though Billions will continue to suffer to keep the world turning. Helping her will likely lead to godhood, as it is imperative that there be 7 'gods' to keep the power flowing as that is what the ritual requires.

Tekhar - HUGE Male deity, God of Death. He wields up to 2 Scythes at a time though the players have only seen him wield 1 so far. He is the real reason magic exists in the world. His magic seems to deal mostly with death so far but he is not truly a necromancer and instead is freeing trapped souls from Telara. Tekhar had long been trapped by a spell from his 7 apprentices and he now seeks to undo the evil his apprentices are responsible for. Tekhar fights for the Billions of souls suffering to keep his apprentices magic flowing. He is an unknown quantity to the players, there is little real knowledge of his character left in the world that has not been corrupted by the church of Telara. He seems the bad guy and releasing the souls from captivity may well end magic in the world. Just the process of releasing the souls has already killed millions. His magic is all his own and he is responsible for teaching the apprentices how to tap into cosmic energies and grow their power naturally. The players should face the dilemma of killing him because it may be for the greater good to prevent further suffering in the afterlife. It is also unknown whether or not Tekhar would try to teach anyone else how to tap into the energies naturally to keep magic in the world. Even should he do this there will be much suffering and death in the world while it reaches a new normal.

I imagine both to be sort of Gishes. Because the players have to fight them I need to have some stats and strategies that are concrete. If the players fail to act then they will devastate the world as they continue to fight and the world will be pushed to the brink of destruction. And the players will die in obscurity. Figured I'd throw this out there for those that enjoy character building. But it's a tall order.

[Doctor Despair]

Have you considered borrowing from any of the Villainous Competitions?