Green doesnt interact with life gain much, so it seems lackluster in that archetype
Since Buyback puts the spell back into its owner's hand, I hypothesize if you pay the Buyback cost on a spell you heisted using Arena 's mechanics, the spell would go back into your opponent's hand
Maybe the vibes are good and you dont want to disrupt that by taking a ten minute turn

Aboshan's Desire Advanced Hoverguard Aerie Mystics Alexi's Cloak Algae Gharial Arcane Lighthouse Argothian Enchantress Armored Guardian Aspect of Mongoose Autumn Willow Benthicore Blastoderm Blurred Mongoose Cairn Wanderer Calciderm Calcite Snapper Cephalid Inkshrouder Citanul Centaurs Cloak and Dagger Clout of the Dominus Control Win Condition (playtest) Crashing Centaur Crystalline Sliver Deadly Grub Deadly Insect Deep Spawn Deft Duelist Diplomatic Immunity Drill-Skimmer Eladamri, Lord of Leaves Elvish Lookout Empyrial Archangel Favorable Destiny Form of the Squirrel Fountain Watch Frost Raptor General's Kabuto Ghosthelm Courier Giant Crab Giant Solifuge Gigapede Gilded Light Glimmering Angel Glimpse, the Unthinkable (playtest) Greater Auramancy Hada Spy Patrol Hanna's Custody Hawkeater Moth Helix Pinnacle Hisoka's Guard Homarid Warrior Humble Budoka Indomitable Archangel Inkwell Leviathan Isleback Spawn Ivory Mask Jolrael's Centaur Kalonian Behemoth Kashi-Tribe Elite Kodama of the North Tree Lightning Greaves Mage's Guile Master of the Wild Hunt Avatar Minotaur Illusionist Mist Leopard Moniker Mage Morphling Multani, Maro-Sorcerer Mystic Veil Naya Hushblade Neurok Commando Neurok Stealthsuit

He has flying, first strike, trample, lifelink, and haste, and at the beginning of combat on my turn other Spiders I control will gain all of those keywords
This card is regarded for the several infinite combos it enables with cards like Deceiver Exarch