An attacking creature becomes an unblocked creature during the declare blockers step of the combat phase if no creature blocks it.

一个攻击生物在战斗阶段中的“宣告阻挡者步骤”中，如果没有生物阻挡它，它便成为一个未受阻挡的生物。

youdao

Evasion abilities restrict what can block an attacking creature. These are static abilities that modify the declare blockers step of combat.

规避异能限制了什么能阻挡进攻生物。这些异能是改变战斗阶段中告阻挡者步骤的静态异能。

youdao

Giant Growth is best used during the declare blockers step when, after your opponent has declared who blocks this round and you receive priority again to play spells or abilities, you squeeze in the 3 damage to win the match with your Giant Growth.

FORBES: Return to Ravnica: Evaluating Golgari