Tools

When refining a build that includes upgrades, you need to know when an upgrade is actually useful and worth getting. A great tool to test this is "Deathchart". It allows you to pick units for both side of the confrontation, and set their upgrades.

Put a zealot on the left side with no upgrades, against a ling on the right side. The zealot will win after 3 hits. Now give the zealot +1 attack upgrade, and he'll win after only 2 hits.

You can find this tool on the sidebar.