It is likely the de facto lesson you get when green and there is no other context going on pushing you towards another lesson
This deck gives up creatures for artifacts that function as elementals, which means targeted removal can risk you overcommitting to elementals, only to be left trashless at just the wrong moment (yes, having no trash is a bad thing)
This elf can grow really big and even give you many scries during each life drain effect
This is a hugely playable card not just because of its Shift cost, but the potential to cast it for free and return discarded characters to your deck at the same time
It also has the potential to be the biggest eldrazi, caring about not just cards exiled with its own abilities, but from anywhere, making it paltry to get plenty of +1/+1 counters on it without casting
Slaughter is a perfect card to pop in the deck too it not only delivers some really targeted removal but also triggers Yshtolas damage-dealing ability thanks to its mana-cost and allows you to draw a card when you decide to buy it back for 4 life