Vyukris's Advanced Shield

A number of creatures (equal to Caster's Intelligence modifier) receive +1 to their Armor Class, for the duration. On each turn, caster must use their action to maintain concentration on the shield, or the spell will fail at the end of the casters turn.

AC bonus increases by +1 at 5th level(+2), and again at 11th level(+3), and 17th level(+4).

When casting using a spell slot of 4th level or higher, caster may choose 1 damage type per spell level(to a maximum of a total of 6 damage types) targets gain resistance to those damage types for the duration.