There are multiple cards that trigger at the end step, and Y'shtola helps to double up on all these effects
(To behold a Dragon, choose a Dragon you control or reveal a Dragon card from your hand.) Whenever a Dragon you control enters, put a +1/+1 counter on Sarkhan
Given how many cards there are that either want to die, or that make sacrificial Thopters or Servos, this cost isnt really a drawback at all, and being able to cheat in one of the big old Creatures from earlier in the list, or even something like Darksteel Forge, which gives all of your Artifacts indestructible, losing three of anything is always worth it
Or you can feed two of your Opponents more cards in hopes of dashing an archenemy at the table you cant deal with
Narset, Enlightened Master Its Thanksgiving It would be disrespectful to talk only about Creatures but leave out non-Creature cards