Blade Ward [Homebrew]

You extend your hand and trace a sigil of warding in the air.  The next critical hit you suffer becomes a normal hit.  Once the spell protects you from a single attack, the spell ends.

The number of attacks the spell protects you from increases when you reach 5th level (2 critical hits), 11th level (3 critical hits), and 17th level (4 critical hits).  The spell ends when it protects you from the listed number of weapon attacks or after 1 minute, whichever comes first.