By the time you get to trial, your landlord will be so frustrated with how long this has taken and how expensive it has been, that he will be inclined to lie on the witness stand to say whatever it takes to get a judgment against you. With the way he's treated you so far, what's one more lie? Don't think that he'd be afraid of perjury charges.

Before it gets to trial, you want to know what the landlord is going to claim, and particularly what he has to say about your defenses. If you know in advance that he is going to claim X and you can disprove that, you'll be ready for him, and expose him as a liar on the witness stand. You may be able to nail him down to the facts so tightly that you can win as a matter a matter of law.  That is what discovery is all about.

There are different types of discovery, and if the landlord fails to answer, or is evasive in his responses, then you can get a court order for him to respond, and pay you money for the effort, in addition to postponeing the trial until he does.  The types of discovery you choose should be based upon advice you receive in a prior discovery consultation, not on your own guess.