uncommon abjuration aura wizard 

Cast [>] somatic

Area 5-foot-radius emanation centered on you

Duration sustained up to 1 minute

You emanate a shimmering aura of protective magic. You and any allies in the area gain a +1 status bonus to AC. Each time you Sustain the Spell, the emanation's radius increases by 5 feet, to a maximum of 30 feet.

Core Rulebook, page 407.