Build a coherent deck and test one change at a time

Start with the plan

A pile of strong cards may not work well together. Say how the deck wins, what it needs first, and what can stop it.

Then add threats, support, and answers that do those jobs. Compare the main deck archetypes if you need help naming the plan.

A normal built deck has 30 cards. You can usually use two copies of a non-Legendary card and one copy of a Legendary card. Some cards add rules or change these limits. Check the exact list in the game's Standard deck builder.

Count useful early plays

Cheap spells are not always good early plays. They may need targets. Check how often your deck can play a threat, defend, draw, and finish at the right times.

Too many costly finishers can leave you with no useful start.

Keep key groups working

A small card may help a whole combo. Removing it may also make a tutor or draw effect less reliable.

Before a swap, ask what job the old card did. A cheaper card should fill that job as well as it can. If the missing card is the whole way to win, trying a different deck may work better.

Test a clear idea

Change a small number of cards at a time. Write a reason, such as: “I need one more early answer against fast decks.” Save the old list and note which matchups may get worse.

Review several games and the choices they gave you. A short win streak does not prove the new list is better. Undo a change if it fixes a rare problem but hurts your usual plan.