Tidehunter is a melee strength hero who is most commonly played as an offlaner or a support hero.
He is a tanky hero with good burst magic damage, damage reduction capabilities, and a slow, but his most famous ability by far is Ravage, which is a potentially tide-turning ultimate that stuns and damages enemies in a huge AoE.
Skills
Gush is usually skilled and maxed first.
Kraken Shell is maxed last, although an early value point can be useful if offlaning.
Anchor Smash is usually maxed second.
Ravage is always skilled (levels 6, 11 and 16). Should be saved for major teamfights in the mid and late game.
Items
Starting Items: Courier and/or Observer Wards, Tangos, Healing Salve, 3x Iron Branches.
Early Game: Flying Courier, Observer Wards, Boots of Speed, Magic Wand.
Core Items: Arcane Boots, Blink Dagger.
Luxury Items: Refresher Orb, Drums of Endurance, Shiva's Guard, Heaven's Halberd, Blade Mail, Scythe of Vyse, Heart of Tarrasque.
Situational Items: Mekanism, Pipe of Insight, Necronomicon, Boots of Travel, Assault Cuirass, Vladmir's Offering, Veil of Discord.