How to get skilled with Olaf & Runes/Masteries Builds for him ?

Please let me know what I need to know about Olaf so that I can get to the point of being able to successfully 1v5 against Intermediate-Level Bots randomly selected in Custom-Mode on Summoner-Rift (especially against a CC-Heavy Composition like Shen + Léona + Mundo + Warwick + Amumu). Are attack-speed runes better ? Damage ? How about Masteries ? Are more defensive masteries like 09/21/00 better on Olaf than something like 21/09/00 or is there another set-up that yields more optimum results ? When are the strongest power-spikes in terms of levels/items built on him ? I usually try to practice this way lately before taking a champion that I haven't used very much against live human-players for further tuning of my picks since I will at least be a bit more practiced on mechanics & have a better idea how to combo skills together before trying to pull it off on humans. Perhaps if anybody here mains Olaf they could do a 1v5 vs Intermediate-Level Shen + Léona + Mundo + Warwick + Amumu then post a replay of it for me to see the strategies or just straight-up respond as to whether such a composition would counter him too hard so that I have an idea of what is weak versus what is strong against him. Thanks !