While Violent Outburst is instant speed, making it better in some spots, Shardless Agent is a creature
This is extremely useful when all you have are reactive cards and you need to find more proactive spells: You get to cast whatever you found useful in the 7-card batch, and regain your reactive cards at the end of the turn
Pathrazer of Ulamog is a great way to obliterate board states while applying pressure, Sepulchral Primordial can build out a big board, and Burning-Rune Demon can search for any of the many options
The difference between a Blue Farm deck and Esika is that Esika is a mana engine in the command zone, while Tymna is a draw engine
His first ability lets you either tap down one of your opponent's key blockers to swing in for that critical attack, or untap one of your own blockers to surprise your opponent during their combat step
You could even build towards Yarok's creature types if you wanted to