This card shows up everywhere , from being cast the old-fashioned way in Standard before rotation to being unfairly played in Legacy and Vintage
For a rundown of all the cards across the set and where you can find them, check out our Collecting Phyrexia: All Will Be One article
Grim Monoliths one of the worst of the fast mana offenders and still pretty darn good
Two-for-ones really shine when your opponents are "playing fair" and they are giving you sufficient time to build your resources
The first Rat cast after it comes down will give you four chances to cast another one, which will give you four chances again
If youre looking to play Magic: The Gatherings non-rotating formats (Pioneer, Modern, Legacy, Vintage) then youll be better off trading for, or simply buying, the exact card you want