I've played as Oak, and I think this guide has a lot of wrong points...
First of all, I've to say that I started playing OAK vs CPU, there I focused on divine justice+surge of faith to win... it worked so good, killing creeps, healing myself, etc... But when I started playing online, I sucked, because a human is not a computer, enemies don't let you farm alone, they're more agresive, they don't die on turrets...what a mess :/
So you should think a lot of human behaibour that can not be plated as cpu
1) Start: Levels and divine justice
-Some DGs can be overpowering as the follow the creeps in... that's nice, they still can't fight you at towers. Fall back, death ward, and kill the creeps while ignoring them. -> BAD! Enemy will kill 5 creeps, you will kill 2 creeps, that's nice?
-Try and stay in play, unattended creeps will restore you if you are hurt. -> There're a lot of priests arround the map ???
about divine justice, it can heal 10% when fighting minions, but at start, if you kill the enemy minions healing yours, your survivant minions will fall down on the enemy turret, so is no reason to heal your minions! And is better that you have monks to heal yourself. That's why you should pick divine justice when your team gets priests and survivant minions can do something vs turrets, never before. At the beginning monks are better.
2)The unmovable: Levels 4-5
-Farm creeps, once you have raise dead 4 pick a place and own it. If someone tries to push you away, you can mess that someone up if all your minions are in play and then heal yourself in the field while them must retreat. You might attack DGs of opportunity, but this can still be counter productive because they can hurt too.
-Once you have surge of faith, you can put a serious hurt on fellow generals, and the DPS you and your concentrated minions can inflict is overpowering. You might notice mana depleting now if you use Surge of Faith too much.
How you pretend to farm if an enemy assasing is farming there? as you can't push him, is hard to farm! Also you think minions are so great and outumber enemies, but they're weak and also only 3-4 survivant creeps on your hand...
Scourge of faith does 300 damage, Penitence II does 400 damage, so scourge don't overpower penitence so much... (as I said, scourge vs computer works so good, but vs human is not as good as indeed)
At level 4-5 neither your dps, not your minions dps, not any combination, will be overpowering
Starting levels are so complicated to OAK, and your guide does not help him.
3) The destroyer: Levels 6-10
-You can demolish enemy DGs fighting near your creeps? -> NOT TRUE, an assasin DG can kill you on 1vs1 fight with minions
-You can demolish towers along the creep path? -> NOT TRUE, oak is not a demolisher
-Since your don't have an Oooffffff! kind of instant 600+ dammage output, consider investing in a universal gadget to nail retreating DGs. -> WHAT? I whant an item that does instant Boulder Roll, how much is it?
penitence at the beginning works as a cry! is like being the lion king, when an enemy aproach you, you penitence him saying "beware, i want to kill you" If the enemy has fear, he will retreat, it will be nice because you can keep farming.
But if the enemie continue agresive to you.. now you have to retreat crying because sure he will kill you
at more advanced levels, penitence will cry : "Beware with your 1000hp, my penitence will deal 600 and slow you!" so enemies low hp will retreat quick, praying not to be penitenced again...
Penintence does a lot of psicological damage, more than phisic!
So I think your guide is good vs cpu, but not vs player.
Thanks anyway for sharing your build and let us discuss the pros and cons