Its placement here is mainly because its a command zone or bust card
Goblins in Magic are known for many things, primarily aggression (Frenzied Goblin), intriguing battle tactics (Goblin Diplomats, Goblin Balloon Brigade), and a wanton disregard for their own lives (Goblin Grenade)
At absolute dirt worst, you get to clone one of your lands to have +1 mana for the turn (or bash someone for 5, I suppose)
If a spell has multiple targets but all of them are the same nonland permanent an opponent controls, Exterminator Magmarch's ability will trigger as long as another opponent controls one or more nonland permanents that spell could target
This problem is further compounded when any card is put into a sleeve
If youve been itching to mess with your opponents a bit and make the game a little harder for them, you might want to consider picking up some of these hexproof creatures, all of which can keep you in the game or sneak through some damage to speed up the game