You need to be sure that being guaranteed to hurt your chances is still better than cutting one of the cards you're thinking about
Here in the Realm of Lorcana were all about working together to gather Lore the competition to get there first is all in good fun
310.4b A battle has the intrinsic ability This permanent enters the battlefield with a number of defense counters on it equal to its printed defense number. This ability creates a replacement effect (see rule 614.1c)
As I mentioned before, things are more complicated than this when you consider cantrips, card advantage, and such, but this should give you a good start for making sure you have the right number of lands in your deck
As long as you aren't compromising your deck too much in doing so, this can be a winning strategy
So that meant Robin Hood - Capable Fighter, Beast - Forbidding Recluse and Hans - Thirteenth in Line make for great inclusions to the list