And if I only play standard, should I even keep my classic cards?
Classic cards is the set that was there when the game launched. In classic mode, you can only use these cards to make decks, as a throwback to the old days. You cannot use these cards in standard.
Keep ur classic cards. they might add newer expacs slowly and u might be interested in them
There’s no point in keeping your Classic cards if you only play Standard. However, note that those cards are “Legacy” and playable in Wild (although they may work differently in Wild). Dusting them means you lose access to their Legacy versions as well (the game warns you of this). So if you don’t play Classic but do play Wild, you should be careful of dusting your Classic cards. None of the Legacy cards can be played in Standard, so if you only play Standard, they don’t mean anything to you.
That said, I would advise against mass dusting of any Classic cards you might have. You might change your mind about playing Classic (or Wild), after all. I would say the best course is to look to them as your first choice for dusting when you need dust to craft something specific for a deck you’re building.
So if I were to dust the “set hero health to 15” Alex classic, I’d lose the new “deal 8 dmg battlecry” Alex as well?
I’m not sure, but I think you will lose both.
No, because “Alexstrasza the Life-Binder” is a completely different card from “Alexstrasza” (and both are completely different cards from “Dragonqueen Alexstrasza”) because they have different names; the fact that both names include “Alexstrasza” is meaningless from a gameplay perspective. Now, you will find in your Legacy collection a slot for “Alexstrasza” which does the “Set hero health to 15” thing. A Wild deck could have both (or all three!) Alexstraszas. That Alexstrasza you will have if you have the Classic Alexstrasza and you will lose her if you dust your Classic Alexstrasza.
those two are different cards, but as an example, if you dust your 4 cost “classic” leeroy, you will also lose your 6 cost “wild” leeroy.
Yep, Leeroy is a good example of the same card that looks different in Legacy and Classic, as opposed to the Alexstraszas, which are different cards. Always look carefully at the name–only if the name is identical are they the same card.