Start with enemy health
Write down health plus armor first. A 17 health opponent with 4 armor is not at 17. Your visible route must reach 21 unless armor is removed separately.
Damage math
How to use a Hearthstone damage calculator
A good damage calculator does not replace your thinking. It gives you a repeatable place to separate board damage, hand damage, hero damage, blockers, and exact lethal.
Split damage by source
Count board attacks, hand burn, weapons, hero powers, and deathrattles in separate buckets. This makes missing one source much less likely.
Subtract blockers
Taunt, Divine Shield, Immune effects, and required trades belong in the cost column. A calculator should show how much damage must be spent before face damage starts.
Check mana and order
Exact damage still fails if the sequence is illegal. Confirm mana, spell damage timing, combo requirements, and whether a minion must attack before a buff.
Use the calculator as a turn habit
Before ending a close turn, run the same scan: health, board, hand, hero, blockers, then order. That habit is the foundation for future LethalCue helper features.