The AI does not seem to complete actions involving the Tournament card. It does not buy a Prize with a Province in hand (see below). It also does not seem to reveal Provinces to inhibit other player's Tournament plays. In general, it fails to reveal Provinces. (It also tends to buy too many Tournaments which is a different issue.)
Turn 17 - Revenge Witch
R draws 2 Coppers, 2 Provinces and a Tournament.
Turn 18 - Revenge Witch
R plays a Tournament.
R draws a Wild Hunt.
R plays a Wild Hunt.
R draws a Copper and 2 Tournaments.
R plays 3 Coppers.
R buys and gains a Silver.
R draws 2 Coppers, a Province and 2 Tournaments.
No cards were discarded or trashed previously before Turn 18 by Revenge Witch. It also discarded the Province following Turn 18 nullifying the power of the Tournament cards.