Thats not to say you cant make a Boros self-mill deck I see you, Osgir players but the card pool in Sultai will probably rebuild better and outpace other colors trying to self-mill

Beast Whisperer Whenever you cast a creature spell, draw a card Elder Gargaroth Vigilance, reach, trample Whenever Elder Gargaroth attacks or blocks, choose one Create a 3/3 green Beast creature token You gain 3 life Draw a card Ohran Frostfang Attacking creatures you control have deathtouch Whenever a creature you control deals combat damage to a player, draw a card Regal Force When Regal Force enters the battlefield, draw a card for each green creature you control Runic Armasaur Whenever an opponent activates an ability of a creature or land that isnt a mana ability, you may draw a card Toski, Bearer of Secrets This spell cant be countered Indestructible Toski, Bearer of Secrets attacks each combat if able Whenever a creature you control deals combat damage to a player, draw a card Non-Budget Enchantment Decks If you are playing an enchantment-focused deck, these are nearly mandatory inclusions to ensure you green card draw strategy

This is my way to get counters on all of my creatures
It's an easy install, with Thanzo continuing to update it to remain compatible with future versions of TCG Card Shop Simulator