Or is it like protect and has an increasing chance of failure each time? It would seem kind of unfair if they could just keep spamming Destiny bond until they killed you/ran out of PP. It does not say anything about this on it's description.
Yes,you can use Destiny Bonds multiple times (until it runs out of PP) and it wouldn't have a chance of failure. It happened to me a lot of times and the only way around it is PP stall.
You can't use destiny bond multiple times in a row because you end up fainting, unless you keep reviving your pokemon and keep doing destiny bond you can do this multiple times (HOPE THIS HELPS) :)