Final answer:
In the game Valorant, Sage's Barrier Orb starts to decay 30 seconds after being placed, leading to the wall's eventual breakdown.
Step-by-step explanation:
The question, 'How long before Sage's Barrier starts decaying?' likely refers to a gameplay mechanic from the popular video game Valorant. Sage is a character in Valorant, known as an agent, who has the ability to place a solid wall, known as 'Barrier Orb'. This wall does indeed start to decay after a set amount of time. As of the current game patch, Sage's Barrier starts to decay 30 seconds after it has been placed. This decay means that the wall starts losing health and eventually breaks down completely without needing to be destroyed by enemy action.