Pretty much every EDH deck plays at least a little ramp
It is natural to wonder how many MTG cards are there in total, but you do not need to know them all to start playing
A creature with Protection from a quality, let's say a colour for simplicity, can't be targeted by spells and abilities of that colour (like Shroud, that's regardless of who controls them)
Next, you need to work out what you want your deck to do, based on the different Magic: The Gathering deck types out there
While there are some diminishing returns with Naban, Dean of Iteration and Snapcaster Mage, since you need mana to cast the spell you flash back from the graveyard, the potential to play a Snapcaster Mage on Turn 4 and flash back a Thoughtseize to take your opponent's best card while also getting to Serum Visions or Thought Scour is pretty appealing