Double white, double black, triple white/blue, triple black/blue, double black/white...
Errr...yeah that's a mana base that I don't want to touch. :-/
Worldpurge is significantly weaker than any of the normal "blow up" spells. Knights especially don't want that, but would rather have them die into the graveyard for maximum ownage. What you want are stuff like wrath of god, damnation, and day of judgment. If you can't afford them, go for stuff like
catastrophe or
Kirtar's wrath. A very common play is to wrath, then Hakkon, and nameless whatever your opponent plays.
Solar tide might be an option if you want a more selective way of killing things off, but I don't recommend it as much, just because Hakkon comes back anyway.
You need to fit 4
nameless inversion into the deck. It's infinite instant-speed removal with Hakkon, which makes it insanely good. In fact, check out other changeling spells to see if there's anything else you like.
Ego Erasure is also another devastating card when combined with Hakkon.
Kinsbaile Cavalier cost too much in general for me to consider them. If I were to use them, I'd put it as a 1-of or as a 2-of, since redundant cavaliers are terrible, as opposed to redundant lieges, which are super awesome. Stillmoon you'd want more of as well.
Knight of the white orchard would help with this deck immensely if you're going second. You need double black AND double white AND single blue by turn 3, so getting you up to 4 lands would help much more. The only issue, of course, is that you need shocklands or borderposts to be able to do that.
My suggestions in summary:
- 2 Kinsbaile cavalier
- 3 Sigil Paladin
- 2 Worldpurge
- 2 Moonlight Bargain
- 1 Hakkon (terrible in multiples again)
- 2 Knight of Dawn
- 2 Black Knight (or sb it)
- 4 WW knights
+ 3 land
+ 4 Nameless Inversion
+ 4 Wrath variants
+ 3 Draw/discard spell similar to compulsive research
+ 4 Knight of the White Orchard
The point of the deck would be to get out a couple of knights out first to trade with your opponent. Then you start drawing into Hakkon and dump him into the graveyard to reanimate him. After that, you take the aggro-control route where you hold the fort with a couple of knights and Hakkon backed by nameless inversion. If the going gets too tough, wrath to reset and start again.
Other suggestions (If you don't want blue):
Tortured Existence
Discard Hakkon to bring back a dead knight. If you aren't too sure on tribal, this works well. Also, this lets you dodge hate. If they relic of progenitus, you can discard a creature to bring back Hakkon into your hand. The only problem here is that you'll have to find a way to discard Hakkon again. It's good for dodging hate or if you aren't really playing a knight deck.
Peace of Mind
The discard offsets the damage you take for Hakkon. Also it lets you essentially keep gaining life, since knights in your graveyard are basically knights in your hand anyway. I highly recommend this if you don't want blue in your deck.