
Frost Blast
Blasts the target enemy unit with damaging frost, dealing area damage and slowing movement and attack rates for 4 seconds. The primary target receives both base and area damage.
Abilities, roles and builds with an explanation for every purchase.

HERO GAME PLANI improve an ally’s survivability with Frost Shield and control the pace of the fight from a distance.
Drifting from battle to battle and sacrificing creeps to fuel his assaults, Lich is always ready to help his fellow heroes destroy their enemies with slowing frost. Should his foes be foolish enough to gather, his bouncing ultimate will ensure their demise.
My recommendation is a starting point. We choose another position together with the team and for its needs.
Help the lane, provide vision and keep the ally alive first; expensive upgrades follow the necessary team purchases.
I contribute through laning, control and movement. I adapt the expensive core route to my budget.
This is an editorial starting plan based on hero mechanics. It is not presented as a match I have already tested or a popularity ranking.
Here is my initial plan: I do my role's job first, then choose the items the team needs. I adapt the order and expensive purchases to the opponent.

Provide speed and regeneration between engagements, fitting a support’s budget.

Adds a protective tool and hides the chosen ally; invisibility does not replace escaping detection.

Lets you use targeted abilities and items from a safer distance.

Moves me or an ally out of danger; direction depends on the target's facing.

Unlocks or upgrades Ice Spire. The exact effects are shown below in the abilities section.

I do not assign one ‘correct’ minute to every purchase. I look at my gold, the next fight and the problem: am I missing mana, target access, control or protection? If an expensive slot will arrive too late, I get a useful answer earlier.
Original Valve icons and descriptions. Cooldowns and mana are shown by level from the data snapshot; talents and upgrades can change the values.

Blasts the target enemy unit with damaging frost, dealing area damage and slowing movement and attack rates for 4 seconds. The primary target receives both base and area damage.

Applies a magical frost shield around the target, reducing damage from attacks against it. While the shield is active, ice magic will affect nearby enemy units every 1 seconds, dealing minor damage and slowing them.

CHANNELED - Hypnotizes an enemy unit, causing it to move towards a point between the two of you and drains a percentage of its current mana.
CHANNELED - Hypnotizes an enemy unit, causing it to move towards a point between the two of you and drains a percentage of its current mana.
The ability affects all enemies in the selected area with a radius of 400. Other abilities can be used while casting it.

Creates an orb of ice that bounces between enemies up to 10 times, slowing them and dealing more damage with each bounce.
Releases an orb of frost that bounces between nearby enemy units up to 10 times, slowing and damaging each time it hits. Each bounce increases the damage for the subsequent bounces. Chain Frost lingers on its last target if it fails to bounce and can bounce again if new targets become available.
These abilities are not necessarily available at the same time. I check the condition beside the name: innate ability, another form or an Aghanim purchase.

Creates an ice spire at the selected point that slows all nearby enemies. When the spire is destroyed, it triggers a frost explosion from Frost Blast at its location. Hero attacks needed to destroy the spire: 4.
Creates an ice spire at the target point, slowing nearby enemies. Destroying it triggers Frost Blast at its location. It takes 4 hero attacks or 8 creep attacks to destroy. Chain Frost can bounce to the spire when no enemies are nearby, damaging it by the equivalent of 1 hero attack. Chain Frost and Frost Shield can be cast on the spire. Each tick of the latter heals it by the equivalent of 1 hero attack.

The hero sacrifices an allied creep, converting its current health into mana for himself and gaining experience for its death.
Sacrifice an allied creep to convert its current health into mana for Lich and give Lich its experience bounty. Begins the game on cooldown and with no charges.
These are fields from the official source. The hero's final values in the client account for attributes and other active mechanics.
Items, slang and real episodes help connect abilities with what happens in a match.