What is the ruling on usury and its conditions, and the ruling on purchasing a house from a usurious bank with an Ijara wa Iqtina (lease to own) contract?

It is forbidden to deal with usurious banks unless no Islamic banks are available, and there is an urgent need to deal with them in a permissible transaction that does not involve prohibited conditions, such as agreeing to an increase in debt upon delayed payment. This is permissible out of necessity, and the necessity is to be judged by its extent.