Bet builder allows you to create a combo bet on maps within the same match. For example, you could bet on the Map 1 winner and a Map 1 player kill market within the same match:
This is treated like a combo bet. If all of your chosen selections win, you'll win the bet. If at least one of your chosen selections loses, you'll lose the bet.
If this feature is available on a match, you will see a 'Bet Builder' button at the top of the match page:
The total odds of your bet builder will be displayed on the market directly depending on what you select:
XP
You will receive 25xp per 1 coin bet on a Bet Builder.
Limits
Bet Builder is only available on select CS2, Dota and League of Legends matches for now. This feature cannot be added on request if it's not available on a listed match.
Bet Builder is only available pre-match. It will not be available once a match is live.
You cannot bet across maps. For example, you can create a bet builder for Map 1, but you cannot add a Map 2 bet into your selection.