The Preferential part is the most important, it means you can vote for who you want but also have the second preference get a vote if the first fails to get a wide enough margin. That first vote however will get additional resources based on vote tally with the next election cycle. If either of the last two majority parties fail to get the necessary votes to hold control and you have a hung parliament, they then have to negotiate with other parties to gain their preference.

Its not perfect but it looks like the best case system I have seen.