Units, damage types and upgrade breakpoints

Lesson

2 of 14

Watch

A written lesson, no video

Practise

Homework 2、a checkpoint、a plan for your next game

After this lesson you will know what your units are really for, and you will be able to work out how many shots any unit needs to kill any other. That one number decides fights, tells you which upgrade to buy next, and explains why some matchups feel hopeless.

What you will learn

• The three jobs every unit does, and why shooting is only one of them.
• Why the game is deliberately unfair in every single matchup, and how to use that.
• How damage types and unit sizes combine, and why shields ignore both.
• How to count shots to kill, and spot the upgrade that removes a shot.
• How to read your opponent's plan from the gas he is not spending.

A unit is three things

Most players think of a unit as some hit points that do some damage. That is the smallest of the three things a unit is.

It sees. Vision is the only reason you know anything. A unit standing somewhere is a live feed of that place, and it costs you nothing extra once it is paid for. An overlord at the edge of a base, a probe left in a corner and a scan are all the same purchase: information.

It hears. Sound is real information. You can hear a mineral line being mined, a factory producing, a fight you are not looking at. Many players have the sound on and never listen. Park a worker near an empty expansion and listen for mining.

It works. Building, repairing, blocking a ramp, holding ground, dying in front of something more expensive. Shooting is one entry on that list.

Before you build a unit, ask which of the three you are buying. An army that can only shoot loses to one that can also see and hear, because it walks into everything blind.

The game is unfair on purpose

The three races are balanced as a whole. No single matchup of two units is. Every unit is crushed by something, and that is deliberate. David Sirlin, who sat in on the class, gave the idea a good name: local imbalance.

It changes how you think about a fight. You are not trying to have the better army. You are trying to arrange the fights where your units are the ones doing the crushing.

Range is the easiest place to see it. Sieged tanks shoot 12 tiles. Reavers and guardians shoot 8. Lurkers shoot 6, and so do goliaths and dragoons with the range upgrade. A hydralisk shoots 4, or 5 with its upgrade. Whoever is out ranged has to close the distance under fire or walk away. That is why a tank line on high ground is so hard to break: it wins the range matchup before the fight starts.

Terran has no melee unit. Think about what that means under dark swarm, where ranged attacks on units inside the swarm do nothing. Every Terran ground unit shoots, so a defiler's swarm can switch off a whole Terran army at once. Protoss still has zealots, dark templar and archons to fight inside it.

Counters come in chains. Carriers beat a ground army. Cloaked wraiths beat carriers that have no detection. Observers find the wraiths. Then a medic's flare can blind an observer, and the chain starts again. Every answer has an answer. Knowing the chain lets you see two steps ahead.

The damage system

Every player should know this cold, and the game never explains it. Two facts combine.

Every attack has a damage type: normal, concussive or explosive. Every unit has a size: small, medium or large.

Together they give a multiplier on the attack:

Concussive also does 25 percent to every building, which is the column nobody remembers.

Three things follow that decide real games.

1. Concussive falls apart against big units. Only three units carry it: the firebat, the ghost and the vulture. A vulture kills a zealot in 9 shots. It needs 26 shots for a dragoon, because once the shields are gone its grenades do a quarter of their damage to a large body. That is 10 seconds against 31. Vultures are for small things.
2. Explosive is wasted on small units. Half of every shot is thrown away. A hydralisk needs 29 hits to kill a zealot. A dragoon, which does 20 a shot, needs 4 shots for a zergling that has only 35 hit points.
3. Normal damage never lies. It does what it says to everything, which is why normal damage units turn up in every army.

Armour comes off first, then the multiplier. Most players have this backwards. The game subtracts armour from the attack, then applies the size multiplier to what is left. On an attack that hits twice, armour comes off each hit, which is why armour matters most against units that hit many times for small amounts.

Shields ignore all of it. Protoss shields take the full attack, whatever the type and whatever the size. Armour does not protect shields; only the shield upgrade does. The multiplier starts only when the shields are gone, and the hit that breaks them carries its leftover damage into the hit points underneath. This is why the first seconds of a fight against Protoss feel nothing like the rest of it: your vultures and hydralisks do full damage until the shields drop.

There is no rounding. Half a point of damage is real. Armour can never take a hit below half a point. Do not round your sums.

Every unit that can attack

This table is printed from the same data the Damage Lab uses, so the numbers here and there always agree.

How to read it. Life is hit points, and for Protoss hit points plus shields. Ground and Air are the attack, with what one weapon upgrade adds in brackets, then the damage type, with x2 where one attack lands as two hits. Range is in tiles, with the upgraded range after it. Armour is the unit's own armour before upgrades. Cost is minerals, then gas.

Two more rules worth as much as the table. Buildings have 1 armour, except each race's anti air structure, which has none. And an attack from low ground up a cliff, or into dark swarm with a ranged weapon, only lands 53 percent of the time.

Shots to kill, and the upgrade that matters

Here is what all of that is for.

Damage is continuous. Death is not. A unit dies on a whole number of hits. Twenty percent more damage buys you nothing until it removes a shot, and then it buys you everything.

That is why upgrades feel useless for minutes and then decisive. You were buying a fraction of a shot the whole time, and it finally tipped over.

Four you can use tonight.

• Marines against zerglings. A marine does 6, a zergling has 35: six shots. One attack upgrade makes it 7: five shots. Two upgrades make it 8: still five. Three make it 9: four shots. The first and third upgrades each remove a shot. The second removes nothing against lings.
• The same fight from the Zerg side. One level of carapace takes the marine's 6 down to 5. Now a zergling takes seven shots. One upgrade added a shot to every zergling on the map.
• Hydralisks into marines. A hydralisk does 10, explosive, so a marine takes 5 a shot: eight shots. Give the marine one armour: 10 minus 1 is 9, halved is 4.5, and 40 divided by 4.5 is nine shots. One point of armour cost the hydralisk a full shot, because armour comes off before the halving.
• Lurkers against marines. A lurker does 20 normal damage and a marine has 40. Two hits, and every marine on the line takes them. That is why marines without medics vanish into a lurker line.

The recipe, which the Damage Lab does for you:

1. Take the attack. Subtract the target's armour, once per hit for a two hit attack.
2. Multiply by the type and size factor from the table. Do not round.
3. Divide the target's hit points by that and round up. That is the number of hits.
4. Now try one more upgrade on either side. If the number of hits changes, that upgrade is a priority. If it does not, it can wait.

Gas as a tell

Every unit has a mineral price and a gas price. The gas price is the one that tells you something. Everybody has minerals. Gas is rationed: it needs a building and workers, and you can see where those are.

So the army that comes at you is a receipt.

• Wave after wave of units that cost no gas means the gas went somewhere else. Something is being researched, built or saved.
• Expensive gas units arriving means the gas is spent. What you were afraid of is either here already or not coming for a while.

Ask one question every time you see his army: what did this cost in gas, and where is the rest?

Answer it out loud. "Three waves of zealots. He has had gas since minute three. It is in tech or it is in the air." That sentence is worth more than any scout you did not send.

Attacks that are not meant to win

Not every attack is trying to kill the enemy. Good players send units to do one of the other two jobs: seeing and working.

• A reaver drop while you expand. The drop does not have to kill anything. It keeps your opponent looking at his mineral line while your new base goes down.
• Corsairs early. They scout, and they stop overlords from scouting you.
• A clump of mutalisks at the edge of his base. They pin his army at home. That is containment, and lesson 13 is all about it.
• A raid that turns back. Sometimes the right move after a raid is to go home with your units alive. You got what you came for: information, or a few workers, or time.

For each, the question from lesson 1 applies. What did it cost, and what did it buy?

Setting up the efficiency matrix

Here is the idea you will finish in lesson 3. For each of your unit types and each of his, ask: how good is my unit against that one, per mineral spent? Write it as a grid. Your army is then a question of which rows to buy, given the columns you expect to face.

The lecture for lesson 3 works through it:

• ►0:30 effectiveness, priced in whatever you are short of: minerals, gas or supply.
• ►3:00 the core derivation.
• ►9:00 a worked example: ten zealots and an archon against zerglings and mutalisks.
• ►16:00 where the model breaks, and why a medic cannot be given a row.

Common mistakes

• Building units for their damage number. A hydralisk's 10 is 5 against marines and zealots.
• Buying upgrades in the wrong order. Check which upgrade removes a shot in the fight you are about to take, and buy that one.
• Forgetting shields. Your concussive and explosive units do full damage to shields. Focus the units whose shields are already down.
• Sending an army blind. A unit that only shoots walks into lurkers, mines and tank lines. Send something to see first.
• Ignoring what did not come. An opponent who never shows gas units is building something. Find it before it finds you.

Practise

Homework 2. Eight short questions, all on this lesson. Try them before you read the answers on the homework page.

1. Medics against sunkens. A Terran pushing into sunken colonies is in trouble while he has fewer medics than the Zerg has sunkens, and safe once the counts are equal. Medics do no damage. Why would their number decide the fight?
2. What a barracks is for. List its uses, on the ground and in the air.
3. Hydralisks into speed zealots. You went hydralisks and he is coming with fast zealots. How badly does it go, and what do you do about it?
4. Dark archon or observer against a lot of lurkers. Count research, buildings, minerals, gas and the time energy takes to charge.
5. What a probe is for, other than mining.
6. Two storms in one place. What do you gain and what do you lose?
7. Why marine and medic is rare against Protoss.
8. Tank shots. How many sieged tank shots kill a zergling and a hydralisk, and how do upgrades on either side change it?

Hints. Questions 1 and 7 turn on how big each hit is, and so on whether healing can keep up. Question 3 turns on explosive against small: the answer is to change what you build, not to fight the matchup you have. For question 8, see the "Careful" box above. Questions 2 and 5 look like filler and are the most useful: they ask you to stop seeing a building as only a factory and a worker as only a miner.

The Damage Lab. Open the Damage Lab and set up the fight you lose most often. Look at the breakpoints list: it shows every upgrade that removes a shot.

Checkpoint