If Costume Closet has left the battlefield or has no +1/+1 counters on it by the time its activated ability resolves, you won't put a +1/+1 counter on the target creature
Additionally, Equipment spells exiled with Nahiri, Forged in Furys ability may be cast without paying their mana costs
They value durability, portability, and anything that speeds up their pre-game setup
Let me explain why, in my typical fashion: Top 10 Two-Mana Goblin Electromancers Goblin ElectromancerGoblin Electromancer Baral, Chief of ComplianceBaral, Chief of Compliance Stormcatch MentorStormcatch Mentor Thunderclap DrakeThunderclap Drake Stenn, Paranoid PartisanStenn, Paranoid Partisan Ral, Monsoon MageRal, Monsoon Mage Curious HomunculusCurious Homunculus Kaza, Roil ChaserKaza, Roil Chaser Battlefield ThaumaturgeBattlefield Thaumaturge Spellbinding SopranoSpellbinding Soprano Here's the thing about the current state of Goblin ElectromancerGoblin Electromancer: It's one of the worst examples of its effect, as is Baral, Chief of ComplianceBaral, Chief of Compliance
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Its neither tied to gameplay nor tournaments, but to Pokmons internal culture and the people who helped develop it