See the Cards of From the Vault: Transform The introduction of double-faced cards was a big moment in Magic history
(Choose any number of permanents and/or players, then give each another counter of each kind already there.) Creature - Whale Filigree Vector When this creature enters, put a +1/+1 counter on each of any number of target creatures and a charge counter on each of any number of target artifacts
It seems silly to have to convince people that the newest iteration of Attune with Aether and Traverse the Ulvenwald is playable, but here goes Imagine that Flower is effectively a Selesnya Guildgate
You can always fall back on exploiting enters triggers, but what about slapping it on Junji, the Midnight Sky or other Kamigawa spirit dragons to get two death triggers
Card draw spells like Steady Progress and Contentious Plan also play into your strategy by allowing you to proliferate
Now that's a pretty solid plan, but it does rely on our opponents doing what we want them to do