This build is for tanky dps bruiser character. If you are being bursted down too fast as olaf or unable to help your team then you're playing olaf wrong. This build will make it so that you can destory the ad carry, get early kills and have brolaf eat a giant sandwich of damage.

Pros
-Good early, mid game
-Can eat loads of damage
-True damage
Cons
-Will be beat by many ranged bruisers with sustain and tanky ability ex) Yorick
-Slightly falls off late game, but I don't really see the fall off that much

I will take ignite and ghost. Ghost is good because 35% movespeed + ult will always guarantee a get away from a fight. It is also good to chase enemies down. Ignite is for finishing off an enemy or reducing the ad carries ability to lifesteal. If you do not like ghost despite this being a reason you can run flash but it is discouraged. Exhaust also can be used instead of ignite for easy chases or hindering the ad carry. It is discouraged because you will not be able to finish people off in lane.

You want to take armor and magic resist runes because the armor will really help you sustain early game and the magic resist will stack up later. You want armor pen so that you wont need to build armor pen items and still do decent damage late game. The move speed quince are for chasing down enemies if you can land your undertow. If you do not like move speed quince then I'd suggest flat damage or more armor pen.

Not really necessary to explain but i usually take 9 21 0. 21 so taht you can completely tank the damage being outputted. If you would like you can switch 3 fomr the AoE mastery into reduce damage by 1-2 and hp regen. 9 is so that you will have that extra power in ignite and extra speed in ghost and plus olaf's passive and mastery attack speed it is pretty good.

Always take undertow first to max. If you need lane sustain or having problems with lane then instead of maxing reckless go vicious strikes. Reckless strikes is if you have an easy or moderate lane that you can farm well and still harass. Always take ulty when you can.

Remember last hitting is the most important thing. It is not worth to harass with your axe if you are missing CS. When using undertow to farm minions, either use it to last hit and harass at the same time or go to the side of teh minion range and line them up as best you can. After go retrieve it and throw it again which will give you very good cs.

I dont really like building dorans on olaf just cause i see it as a waste of gold. Building wriggles will give you better chance to cs and have a small amount of armor plus a ward so that you wont get ganked and won't have to spend on other wards. Depending on the team comp you can choose merc or ninja tabis. CDR boots are not recommended. I will always build a giants belt. If you are farmed up enough you have either the choice in frozen or warmog's first. If you want a small amount of extra damage and alittle bit more chase potential go Frozen. If you have a neutral/hard lane choose warmog's. After build ur atmas for the armor and damage. Also if you choose not too then build the next hp item either the warmog's or frozen mallet. GA is usually good by now since you will be tanky and will want to survive just incase you are bursted down (this will only happen if the other team has super high AP carries like veigar and le blac). The next choice after GA is either building more armor, a randiun's or a thornmail or frozen heart or if they are heavy ap, either a Maw or a force of nature. I almost forgot, if you are having a trouble with ap top then build a hexdrinker early. If you want damage you can build a blood thirster as the last item.

Build is for TANKY DPS Olaf. This build is for sustain, damage and eating damage for your team. Remember farm is essential and 10-15 cs = one kill. You will have amazing sustain and damage early game. Early kills will help you there but farming is very important. Don't be discouraged if you are not gaining kills and getting assists late game. This is your job. A tip though, if you want to be that OH YA KS MAN kind of person then undertow and autoattack until you see 2-3 bars left of hp and then reckless swing. You will get the kill. Good luck and eat loads of damage!