23.4 Known Issues - Bug Report - Hearthstone Forums (blizzard.com)
It is known issues that:
" * Brann Bronzebeard’s Summit Campfire’s effect does not match its text."
Actually the skill works as designed: Affects opponents have acted before Brann casting this skill and benefits companion which acts later. But the design make nonsense. It should cast against all opponents and checks the “acted” condition to take effect when companions cast skills against them.
Another issue about this skill : Lvl3 is identical to lvl4.