The Galio Indefatigable card says I don't deal combat damage. What does it mean? And how does this card work?

Galio, Indefatigable possesses a static ability that modifies how he interacts with the combat system. Here is a breakdown of what that means and how he functions:

"I don't deal combat damage"

In a standard combat showdown, units sum their Might to determine the total combat damage dealt to the opposing units (Rule 460.2.a).

Because Galio has the text "I don't deal combat damage," he contributes 0 to your total combat damage, regardless of his printed Might of 6. Even though he participates in the combat (he is present at the battlefield), he performs no action during the Combat Damage Step to damage the opponent's units.

How Galio, Indefatigable works

Galio is a defensive powerhouse designed to soak up damage rather than output it:

• [Tank]: This keyword means that when your opponent deals combat damage to your side of the battlefield, it must be assigned to Galio first before any other units present can take damage.
• [Deflect]: This makes it more expensive for your opponent to target him with spells or abilities, as they must pay an additional cost of 1 Power (of any Domain) for each time they choose him.
• Combat Interaction: Since he deals 0 damage, he is essentially a "meat shield." He will survive combat as long as the total damage dealt to him by the opponent does not equal or exceed his Might (6). Because he does not deal damage, he also makes it easier for combat to end in a tie (assuming the opponent's units are not destroyed by your other units), which can be strategically useful if you have cards that benefit from tied combat, such as Symbol of the Solari.

In short: Galio exists to protect your other units from being destroyed and to provide a resilient, hard-to-remove presence on the battlefield, while leaving the task of dealing damage to your other units.