What are offerings in Holo Battle Interlink?

You pick the offering before each boss fight, so the buff can match the boss in front of you. Each weekly cycle has three routes, and every route has its own Alpha Aniimo encounters and environmental mechanics. A buff that helps on one route may do little on another.

Stars come from damage dealt to the boss before time runs out, at one star per million damage. Your best star rank is recorded separately for each route. In practice, a good offering is one that raises your damage inside the time limit. You get one revive per run, so a defensive pick only pays off if it keeps you dealing damage.

The offering is a team choice. If you join someone else's team to help them raise their star rank, you fight under the buff that team picked, and you earn support rewards for helping.

Offerings versus the season buff

Offerings are a different thing from the party-wide season buff. You unlock the season buff by building up star points, with a star buff opening at 48 stars, and the buff and its progress stay with you for the whole season. An offering lasts only for the fight you chose it for, and you choose again before the next one.