The Ogre Club is an item purchasable at the Main Shop, under Attributes.
Additional information
One Ogre Club grants a total of {{#show:Ogre Club|?active health#}} health and {{#show:Ogre Club|?active health regeneration flat#}} health regeneration (and {{#show:Ogre Club|?bonus strength#}} attack damage to strength heroes).
Trivia
In DotA, this item is named "Ogre Axe". The reasoning for the name change in Dota 2 is unknown.