Cards like Lord of Extinction are easily able to swell to a point that they kill in a hit

MTG Lost Caverns of Ixalan Explorers of the Deep Decklist Heres the full decklist for the Explorers of the Deep Commander deck from Creatures to Lands: Creature: 29 Cards 1 Benthic Biomancer 1 Coralhelm Commander 1 Emperor Mihail II 1 Herald of Secret Streams 1 Kopala, Warden of Waves 1 Master of the Pearl Trident 1 Merfolk Sovereign 1 Seafloor Oracle 1 Surgespanner 1 Svyelun of Sea and Sky 1 Thassa, God of the Sea 1 Thieving Skydiver 1 Deeproot Elite 1 Realmwalker 1 Cold-Eyed Selkie 1 Kumena, Tyrant of Orazca 1 Prime Speaker Zegana 1 Tishana, Voice of Thunder 1 Vorel of the Hull Clade 1 Zegana, Utopian Speaker 1 Metallic Mimic 1 Merrow Reejerey 1 Sage of Fables 1 Stonybrook Banneret 1 Evolution Sage 1 Kioras Follower 1 Merfolk Mistbinder 1 Merfolk Skydiver 1 Tatyova, Benthic Druid Sorcery: 4 Cards 1 Curse of the Swine 1 Ravenform 1 Explore 1 Kodamas Reach Instant: 7 Cards 1 Ruinous Intrusion 1 Quandrix Command 1 Aetherize 1 Rapid Hybridization 1 Beast Within 1 Inspiring Call 1 Growth Spiral Artifact: 5 cards 1 Arcane Signet 1 Commanders Sphere 1 Simic Signet 1 Sol Ring 1 Swiftfoot Boots Enchantment: 6 Cards 1 Kindred Discovery 1 Reflections of Littjara 1 Branching Evolution 1 Hardened Scales 1 Simic Ascendancy 1 Deeproot Waters Land: 36 Cards 1 Alchemists Refuge 1 Hinterland Harbor 1 Karns Bastion 1 Mosswort Bridge 1 Temple of Mystery 1 Vineglimmer Snarl 1 Command Tower 1 Llanowar Reborn 1 Myriad Landscape 1 Path of Ancestry 1 Reliquary Tower 1 Rogues Passage 1 Secluded Courtyard 1 Simic Growth Chamber 1 Temple of the False God 1 Unclaimed Territory 7 Forest 13 Island New: 13 cards 1 Hakbal of the Surging Soul 1 Xolatoyac, the Smiling Flood 1 Mist Dancer 1 Ripples of Potential 1 Wave Goodbye 1 Bygone Marvels 1 Deeproot Historian 1 Topography Tracker 1 Tributary Instructor 1 Singer of Swift Rivers 1 Commit /// Memory 1 Merfolk Cave-Diver 1 Nicanzil, Current Conductor Simic colors deploying +1/+1 counters are among MTGs most reliably well-performing archetypes

The same card from a recent reprint set often costs a fraction of that price while playing identically
You can sacrifice every other creature in the deck to its casualty ability, and the guaranteed copy effect means Parnesse plays better with your commander, rather than the other way around
The palette perfectly relates the insidious nature of whats happening
On top of that, there are a multitude of combos that can be executed once Derevi is in play