"Earwig Squad" is a 5/3 black goblin rogue creature spell printed for the Magic the Gathering expansion set known as "Morningtide." This is one of the many cards printed in Morningtide which encourages players to build decks around a certain theme or "tribe." In this case, this card encourages players to build around goblins and/or rogues. Morningtide is the one expansion set that encourages building around specific creature types for the most part.
The converted mana cost for Earwig Squad is five. You will need two black mana and three colorless mana to bring Earwig Squad from your hand and onto the battlefield. For what Earwig Squad can do, the converted mana cost is pretty reasonable enough for the most part.
What does Earwig Squad do in the first place?
For what Earwig Squad can do, you should play this in a black control deck. That way, you can get the most out of Earwig Squad. To start things off, Earwig Squad has an alternative Prowl cost of one black mana and two colorless mana. You can pay this cost if you manage to do combat damage with a goblin and/or rogue creature. If you do, you can pay the Prowl cost instead of the actual mana cost.
Earwig Squad has a good power and toughness for the most part. Its main ability lies in the Prowl cost. In this respect, you can search a target opponent's library for three cards. Then, you get to Exile those three cards from the game.
A good combination would be something that sends Earwig Squad back to your hand. Then, you can attack with a goblin and/or rogue creature. Doing so lets you pay the Prowl cost and put Earwig Squad back onto the battlefield. You can repeat the process over and over in a matter of turns. In this respect, you have done some damage to the opponent's library.
Overall, Earwig Squad is a pretty interesting card. The main drawback of Earwig Squad is that you are practically forced to play with one creature type and one sub-type. You can use this in a control deck. However, you are going to need goblins and/or rogues. On top of that, you will have to play aggressively with those goblin and rogue creatures. If not, you probably will not get much use out of Earwig Squad. In a sense, you need a black aggressive-control deck with goblins and rogues to get the most use out of this card.