As long as Cikatro Vizago is in any arena, Broken Horn gets "Forewarning: Gain 1 build point when your next build step starts."
Keywords
Forewarning
Forewarning: [Effect]: A static, layered effect that means, "Whenever this unit is attacked, you may predict the number of hits that will be rolled for that attack. If you're correct, gain the [effect]. For example, a unit with "Forewarning: Gain 2 Force" will give you 2 Force if you guess the number of hits rolled correctly.
Shields
Shields X: A cumulative, static ability that means, "The attacking unit gets –X power against this unit." Shields only matters when attack dice are rolled. If you give a unit Shields after your opponent has rolled for damage, it doesn't affect the roll.