I see many people confused by what is standard legal, what isn’t, and when does it change, so I thought I would attempt to simplify things using a two cups analogy. Basically, whatever is in the cups is legal in standard, but the cups have two key restrictions:
1) They must contain the most recent two blocks
2) Each cup can hold AT MOST a block (Theros, Born of the Gods, and Journey into Nyx form a block) and a core set (Magic 2014 was a core set).
If both cups are full and you have to add a new set to the mix, you empty the older cup and start filling it with the new set.
Let me know if there is any way to make this easier for you to understand so I can help out!
Guys I dun goofed before and it said AVR not Dragon’s Maze, but it is correct now!! As much as I love the Angel’s from AVR, Dragon’s Maze… well it was a set that happened :D