By having a high defense early, you can block attackers for a long time
Colorless: Skullclamp, Ichor Wellspring, Mishras Bauble, Mask of Memory, etc
Weve had a smattering of otters in Magic for a few years, but Bloomburrow brought a whole romp of otters (which is the coolest of the various words used to describe a group of otters!)
Sin, Spiras Punishment Sin, Spira's Punishment could be fine top-end for a self-mill deck that utilizes mechanics like delve or cards like Relic of Progenitus to sculpt the graveyard and give them plenty of control over what you get back
Dance of the Tumbleweeds Hear me out: This is a terrible Rampant Growth
In short, Ashaya is a tank, and all you need to do is give them fuel to win the game