A Boost costs $1 and adds 1 point to the side you pick. Each Boost also adds to the battle's prize pool.
Each wallet can buy 2 Boosts per battle, on either side or split between both. In a tournament the limit of 2 applies per matchup.
Boosts close when 80% of the battle time has passed. In a 24 hour battle the last Boost can be bought 19 hours and 12 minutes after the start. In a 1 hour battle it is 48 minutes.