There are no pointers. Reg is a weak DG, and almost never used in competetive play, and basically never used by the winning side in competetive play. DG comes down to basically four demigods - UB, Erebus, Sedna, and Oak. Rook and TB and Reg can be used in some situations, but typically using them gives you a disadvantage. QoT is almost never useful.
The problem with Sedna is that all a Sedna has to do is stick her bishops on you, let them whittle you away, while she ignores you. If you want to take the time to auto-attack the bishops, she can just pop them out every 45 seconds. Later in games when towers are down, all you can do is try to kite and outdamage the bishops heals.
Builds without snipe can be succesful... Which is not to say that they are better then builds that do use snipe. Because there not. Especially if you are a premade. Snipes work out to countless kills that would not have happened otherwise. A snipe reg can basically push towers the whole game and give support snipes when his teamates call. And we all know how important those goldside towers are on Cat. d
Your right those are your 4 bread and butter demigods.
In a serious match you want to have atleast 2 of them in say a 3 on 3. Or 3 whichever you prefer.
However those are your typical frontliners, and all the demigods are viable as support for them as long as your frontliners are compitent.
Try taking on me and my UB partner 2v2 on livithian and ill play Qot.
Regulas in the hands of a premade equates to countless kills on the strongside, were as he is passive on his side. Not to mention serious tower pushing.
And Rook on cata is op, put him with a sedna and an erubus who know how to use towers like the rook does and defend pivotal points endgame.
Your right those are the 4 main, and you want atleast a couple. But some of the best combos involve one of the support demigods with the frontliners.