Even if it sets you back a bit, paying only 2 mana for Devastation Tide means you will likely have a reasonable amount of mana to reestablish your board that turn
It costs the extra mana, a colored pip no less, but getting to cast a spell with mana value two or less for free makes it well worth the increased cost
For four mana, you get a Blue and Black 3/3 with hexproof that reads, Whenever a creature card is put into an opponents graveyard from anywhere, you may have Lazav, Dimir Mastermind become a copy of that card, except its name is Lazav, Dimir Mastermind, its legendary in addition to its other types, and it has hexproof and this ability. The key thing here is how often they can change their form, because it means you can always have the best possible thing at the table, and it even has hexproof
An escalating army of Tarmogoyfs is hard to argue with
To be precise, the best prices I've tracked down for Perfect Order (the upcoming set that launches in just a few days) have been at Miniature Market, and it's not even close