The Destined Thief can't be blocked.
, : Another target creature you control can't be blocked this turn.
Whenever one or more creatures you control deal combat damage to one or more players, draw a card, then discard a card. If you have a full party, instead draw three cards.
(02/10/2025)
Once a creature you control has been blocked, activating The Destined Thief's second ability targeting that creature won't cause it to become unblocked.
(02/10/2025)
If a creature has more than one party creature type, and there are multiple ways to count that creature that could result in a different number of creatures in your party, the highest such number is used. For example, if you control a Cleric and a Cleric Wizard, the number of creatures in your party is two. You can't choose to have it be just one by counting the Cleric Wizard first as a Cleric.
(02/10/2025)
If you have a full party, you won't discard at all when The Destined Thief's last ability resolves.
(02/10/2025)
To determine "the number of creatures in your party," check whether you control a Cleric, whether you control a Rogue, whether you control a Warrior, and whether you control a Wizard. The number is the total number of those checks to which you answered yes. Each creature you control can be counted for only one of those checks.
(02/10/2025)
Some cards refer to you having a "full party." This is true if the number of creatures in your party is four.