Miirym, Sentinel Wyrm

Flying, ward {2}
Whenever another nontoken Dragon you control enters, create a token that's a copy of it, except the token isn't legendary.

Riku of Many Paths

Whenever you cast a modal spell, choose up to X, where X is the number of times you chose a mode for that spell —
• Exile the top card of your library. Until the end of your next turn, you may play it.
• Put a +1/+1 counter on Riku. It gains trample until end of turn.
• Create a 1/1 blue Bird creature token with flying.

Kalamax, the Stormsire

Whenever you cast your first instant spell each turn, if Kalamax is tapped, copy that spell. You may choose new targets for the copy.
Whenever you copy an instant spell, put a +1/+1 counter on Kalamax.

Saheeli, Radiant Creator

Whenever you cast an Artificer or artifact spell, you get {E} (an energy counter).
At the beginning of combat on your turn, you may pay {E}{E}{E}. When you do, create a token that's a copy of target permanent you control, except it's a 5/5 artifact creature in addition to its other types and has haste. Sacrifice it at the beginning of the next end step.

Ureni of the Unwritten

Flying, trample
Whenever Ureni enters or attacks, look at the top eight cards of your library. You may put a Dragon creature card from among them onto the battlefield. Put the rest on the bottom of your library in a random order.

Eshki, Temur's Roar

Whenever you cast a creature spell, put a +1/+1 counter on Eshki. If that spell's power is 4 or greater, draw a card. If that spell's power is 6 or greater, Eshki deals damage equal to Eshki's power to each opponent.