Spiders-Man, Heroic Horde can come down early for just 2 mana and generate tokens and life if you cast it with web-slinging
Its less deep than Magic, but the gameplay is solid, and the core mechanics provide a lot of opportunity for future card designs
If you prefer your defenses to come in the form of surprise spells, you could replace Aven Courier and Floriferous Vinewall with Simic staples such as Rapid Hybridization , Krosan Grip , Nature's Claim , or counterspells like Negate or Swan Song
5 cards of rarity Rare or higher
Picking up another Engineered Explosives stand-in will help there, and Blast Zone contributes to Amulet Titans ability to find answers to absolutely every problem given enough time and mana
I think that the most powerful mill pieces are the ones that require minimal extra work from the mill player, and Mindcrank is a prime example