“They can’t block what they can’t catch.” — Unnamed Rogue, Ravnica
However, MTG is a game of priority passes. If a creature is "unblockable," the defending player is incentivized to ignore the Blocking step entirely and interact during the Declare Attackers step or earlier. unblockable mtg
Wizards of the Coast no longer prints “unblockable” on new cards. It has been replaced by the keyword “can’t be blocked” (e.g., “This creature can’t be blocked.”). The functional effect is identical. “They can’t block what they can’t catch