Halo generated a five-foot-wide, sharp-edged gold hoop that he could move at will, and which could generate forcefields and lasers. He could use this to fly, but preferred to stay on the ground during combat.
His lasers were continuous beams of golden light, and he could generate multiple beams at a time.
His forcefields were immobile and generated around the ring; in order to protect himself he had to recall it to his side and remain in one place.
It's possible that he could vary the size of the hoop, but even at its largest and under the influence of Vista's power it only reached twice its usual size.
↑"Halo packs a special ring. Kind of like Sundancer, but the thing doesn't burn. It's a hoop with a cutting edge, and it acts as a forcefield generator and spits out lasers." - Imago 21.3
↑ 3.03.1As we approached, I found Halo in my reach. My swarm approached him, and his halo zipped to his side, five feet in diameter and razor-edged. A force field protected the hero.
He was still rooted in place. One less person to deal with. - Imago 21.3
↑ 4.04.14.2Halo. Sundancer. A handful of masters with projection powers. A cape with a giant mask.
All powers that made stuff.
A ring of razor-sharp gold that produced forcefields and lasers. A miniature sun. Soldiers of stone. A golden mask. I had each of them make the individual objects as big as they could get.
[...] Then I accessed Vista. And I made it all bigger.
I pulled the capes out of the way as the various weapons entered the fray. The sun was as broad across as a skyscraper was tall, the halo was only twice its usual size, firing a substantially sized laser. - Speck 30.5
↑We've got Rosary in a combat mode, and Halo's not in the air, as far as I can see, so they're obviously geared up for a fight. - Imago 21.3
↑Rays of golden light speared into the swarm. They were persistent, unending, five steady beams that concentrated on areas where the bugs were thickest. Halo. - Imago 21.3
↑Leviathan had more than halved our ranks with the wave. [...] The Armband spoke. Losses are as follows: Debaser, Ascendant, Gallant, Zigzag, Prince of Blades, Vitiator, Humble, Halo, Whirlygig, Night, Crusader, Uglymug, Victor, Furrow, Barker, Elegance, Quark, Pelter, Snowflake, Ballistic, Mama Bear, Mister Eminent, Flashbang, Biter… - Extermination 8.3