Ok, so I have got some legendaries and epics out of my packs, that I think won't see any play in my decks and I almost never see in the current meta or the meta before. But I'm looking for some advice before I just randomly dust some potentially good cards. As a reference, I am planning on playing DK Warlock, Hunter, Mage and maybe DK Rogue or DK Druid. (And I'm a F2P).
Man, I love Mana Geode. That's a very strong card which might be worth keeping for now, unless there's something specific you really need. I haven't seen it too much recently (I did in Un'Goro, and it should still be OK now), but it can do serious work against token decks. But if you really never play priest, well, maybe.
Well my stance on dusting as a F2P player myself is dust everything that you don't use and doesn't have crazy good potential. So if a card could be absolutely insane in the right deck but that deck doesn't exist yet I'll hold on to the card otherwise everything I don't use is dusted. In your collection I think lunar visions and luckydoo have potential but the other cards suck and are prob safe to dust!
hang onto the KK just because of the no dupe legendaries out of packs. the rest you can dust if you want but you will never know where the meta will shift and if you ever play wild some cards see extra value.
MInd Games is POSSIBLY a keeper but if you need dust, dust them all. I wouldn't sweat getting KK again in your classic packs either unless you plan on buying a bundle of classic packs and have all the classic legendaries you want. If you get him again from the weekly tavern brawl, well I guess it's another 400 dust.
Most of those are dust candidates, but I can give two solid bits of advice, and you can disregard anyone who doesn't include these on their response imo.
There is not a CURRENT meta. The expansion is only a week old and considering the how flexible un'goro was plus OFF, it will probably be a month or so before the meta is truly set.
King crush is a legendary. See where the meta goes because maybe he somehow becomes playable. Idk. Also keeping it will make sure you don't get it again in the future. It would really suck to dust it then open some promo pack later and get him again.
Just ask yourself, if 400 dust worth it? And is that the difference between you and a killer legend worthy deck?