Arbor Ales: Monsoon Saison

[AnthonyD]

Been drinking this a fair bit recently and love it to pieces. A really big 6.4% beer.

This is what I've managed to find out about it so far:
"Arbor Ales' take on a Saison but brewed with lots of experimental hops and spiced up with liberal additions of cardamom and coriander."

"Freestyle Fridays #36. A Cardamom and Coriander Saison

6.4% ABV 500ml bottle

Bristol-based Arbor Ales have been brewing quality craft ales since early 2007. All their beers are brewed using the finest ingredients: Maris Otter malt supplied by Warminster Maltings, Britain’s oldest working floor maltings, and whole hops from Charles Faram of Malvern. "

Anyone got any ideas on how I'd start to emulate this? Also I doubt I'd know where to start with the cardamon or corriander! What type of quantities would I be looking to use and do I add them to the boil or to the primary or secondary? How do I make sure there are no nasties to infect the beer?

Any ideas much appreciated!