Whoa, whoa. Masterfrost in Frost Presence is a NO GO. The run speed and haste increase are WAY more valuable to be replaced. I could explain but this is obvious since it's basic knowledge.
Why improve frost presence? Simply because you need to reach 31 points in frost and if you're using a 2h masterfrost build, annihilation is not worth it and nerves of cold steel/threat of thassarian are useless. Rather have an small increase in runic power gain than nothing.
Third of all, in pvp, popping your defensive cooldowns too early is a very bad idea. Only if you know you're going to get a huge burst should you use AMS quickly. There are trinkets to get you out of those rough situations. Knowing when to use the skill is crucial and I will rather land a CC and tear down the partner, or, if in a bg, give myself enough time to control the situation is so much better than wasting it. Also, your opponents are not stupid. If they see you AMS-ing right at the start they'll wait until you're exposed to CC you lol.
Appart from that, nothing else to say.
For toshika: Something that came up to my mind while writing this.. You should specify that this is a 2h masterfrost guide and not simply a frost pvp guide because there are at least four combinations for frost.
-Regular DW Frost
-DW Masterfrost
-2h Masterfrost
-Regular 2h Frost
Obviously there are prefered ones but you should always be specific when you want to write a guide.
To finish, thanks Ceironn for completing what I meant with keeping obliterate in your bars. Those are the most relevant cases.