The way ante functions in Kocka:
When Contract from below is played the player casting the spell exiles the top card of their library, that card is added to the ante.

If the anted card is a basic land it is not anted but does still stay exiled.

At the end of the match if a player with anted cards lost the match, those cards are moved into the winning players draft pool.

If a player wins with cards in the ante they stay in the original draft pool.