Lich is a ranged intelligence support hero who is unique in Dota 2 in that not only is he one of only a handful of heroes who can deny their own creeps, thus denying the enemy experience an gold, but he is the only hero in the entire game that gain experience by doing so.
Skills
Frost Blast is skilled second but usually maxed first, as it is Lich's spammable nuke.
Ice Armor is skilled and maxed last. Use it pre-emptively on your cores in the mid & late game.
Sacrifice is skilled first but usually maxed second. Try to deny creeps outside of enemy experience range.
Chain Frost is always skilled (levels 6, 11 and 16) and is used in the chaos of teamfights/ganks or to ensure a kill.
Items
Starting Items: Courier and/or Observer Wards, a set of Tangos, a Healing Salve, Gauntlets of Strength, Iron Branch.
Early Game: Flying Courier, Observer Wards, Boots of Speed, Magic Wand, Bracer.
Core: Tranquil Boots, Mekanism.
Luxury Options: Drums of Endurance, Force Staff, Ghost Scepter, Heaven's Halberd, Eul's, Scythe of Vyse, Vladmir's Offering, Veil of Discord, Aghanim's Scepter.
Situational: Sentry Wards, Dust, Gem, Smoke, Nekronomicon (push), Diffusal (counter hex), Orchid (vs. mobile heroes), Boots of Travel (late game), Pipe of Insight (if you didn't go for Mek).
