I wasn't saying that you would get CoN Erebus + CoN Oak... the point I'm making is that it is extremely difficult to get away from that combination and you can literally overextend by just standing on a flag. Let's say you walk up to the mana flag and not one but both of them port on you. What do you do?
They have full hp, it takes time for your spirits to "munch" up demigods, and a level-ed up mass charm completely screws them up (let's say they are at level 8 and they didn't take mist. They'll probably have 2 points in charm which is a 6 second stun if I recall correctly). Yes, you can interrupt Mass Charm but if you're doing the whole pent+spirits == rape then that is no longer an option. You can choose to save Pent to interrupt MC or you can choose to use Pent + Spirits off the bat for damage.
Now you've got Surge of Faith (nukes your spirits halfway, if you're suffering from the minion hp bug he might get some insta-kills) -> CoN -> Pent while Erebus bites you. Wait 4 seconds so that Pent comes off of CD, start casting MC. Now what, you sigil...? Now, Oak can either blow Pent on you again (enabling you just to port away) and you've lost 750 gold to their 500 or try to save it and get a kill anyway (they can chase wayyyyy past towers. Oak has Shield III, Erebus has BS). Even if one of your teammates ports to try to save your ass, there is 750 gold again...
So what's your options? Never walk up and cap a flag? Back away from a flag whenever you see a port coming in (oh, I'll abuse that, I'll flash fake ports to you alllllll game)?
Sure, I'm bringing up 2v1 here and this means that your teammates probably are dominating the hp side of the map (unless one of them ports, that is...). But that is all CoN Oak + Blood Erebus do. Gankgankgankgankgank. That's the point I'm making: other demigods have a way of surving it at level 8. Sedna has heal to stop the Bite/Pent debuffs, Oak has Shield III, Erebus has Batswarm, Rook (should) have at least a few towers up before walking up to cap a flag anyway.
Now maybe I'm misunderstanding your sekkrit build up to level 8 but it is probably:
4. Pent II + Ward II
5. Surge of Faith
7. Pent III + Ward III
8. Shield I or Divine Justice I or Soul Power I
with one of the skills at 8 possibly taken at either 3 or 6 and Pent being knocked down in priority.
Now, I'm not a fantastic CoN Oak and certainly not a good Erebus. But I can theorycraft as well as the next guy and that's how I would play against you knowing your build and strategy before hand. That said, if I was the Oak, I would just go counter-minion build anyway :shrug:
Even with 2 mana helms (which means no currency. not a big deal, but still), if you're spamming Ward (all of 200 mana, I know, but lets say you lay out at least 3 flags in a period of 4 minutes, that's still one ability) AND Surge AND a high-level pentitence and if you don't have Divine Justice... I can oom you by looking at you. -.-