There are many, many ways to get rid of cards for either cash or different cards
If the triggered ability can't determine the information it needs, or if it can't find the objects it expects to find in certain zones, those parts of the effect just do nothing
(2024-11-08) For many playtest cards, youll need to make a generous assumption that basic game rules would be updated to allow them to work
But it wasn't really until Invasion that the occasional flirting with gold cards and mechanics really came into its own and the real power of gold cards was unleashed, alongside split cards and later hybrid
Note that if a spell had no other effect except to draw you one card (such as Reach Through Mists), then it would not provide card advantage
It costs a hefty 6 mana, but you immediately get a 5/5 menace haste and trample creature and an incredible sacrifice trigger on attacks