I've spent far too long working on Erebus over the past week.
True story from last night playing Pantheon, I had a full bite skill, full vampire minions, full stun, and half morale and 2 bat swarm. I had all level 4 idols. My "allies" were 2 QOTs. We had the enemies, Sedna and 2 Rooks pinned down to their base on a conquest on Inferno.
We had a full army including giants, with level 3 armor upgrades and level 2 weapons. They manage to kill our offense. They take back their flags, they run to the artifact hut, they bought some items and then the Rook with 4000 health had almost 9000+ within the next 5 mins. After another hour of fighting a losing battle, they finally kill us. 3 level 20 generals couldn't stand against level 14 assasins with high priced gear much less when they maxed out at 20. At the height of our push, I was broke. I sold a few idols to get the money to try to run to the artifact shop for something to help us out but, there was nothing to be done.
The simple truth is that Erebus, and any general for that matter; plateaus really low in terms of decisive power. I managed to push quickly and power level him to 15 and higher. With a higher level and some decent luck, we pushed them back but, I couldn't finish the job because there wasn't any way for me to stop an upgraded Rook as the vampire lord. His max bite barely dented his upgraded health and then the hammer fell. By then end of the game, I was getting the super pimp-slap that literally killed me in less than 3 seconds, not even a hammer fall. I'd go up to the rook for a charm, Sedna would silence me, I'd die.
I've played Oak for the two weeks before this. Oak has decent spirits. His attack boost from spirits allows him to be competitive. His final stand allows him to break a defensive stand by letting him finish killing any single structure. He's got great team potential with his penitance, his judgement, and his shield depending on the size and configuration of his team. However, without someone to act as a spear to his shield, he also can't push worth a damn on his own against say the Unclean Beast and Torch Bearer.
Sedna is a healing beast. She blocks enemy healers, she silences demigods, She can even summon up to 4 yetis to slice and dice enemy demigods while she runs away to heal. Still, even with a maxed out Pounce, she'll never be able to kill a powered up rook.
3 assasins vs 3 generals will end with the generals losing every time assuming equal skill. I'll grant that the generals will make some ground at the beginning. They do get Monks to start. But, after a bit of time, the generals will run out of gas just short of the finish line. The assasins will have their combos starting, the game will then drag to a fitfull end.
What to do to fix the problem? The true power of a general in early game does lie in the idols. The extra monks give just enough push to start breaking down the defenses. However, by the time the assasin reaches level 10, they can ignore the minions in favor of nuking the generals and taking out the troops at the same time. At this time, the general needs to be a few levels higher or else, he's already pretty much on the run.
How about lowering the level requirements of the generals and raising the cap to 25 so they can improve their morale and minions without taking a huge hit on their active abilites.
Alternatively, remove the bounty from General's heads. As the generals are already weak targets with high levels, when they die, Assasins get a huge bounty that goes to better equipment and more insane gear. Remove the bounty from generals and then Assasins can either target other assasins or buildings for bonus gold. A general can stay at the front lines assisting his troops without feeding the enemy economy.