Nyla, Shirshu Sleuth's second ability has an "intervening 'if' clause." That means the ability won't trigger at all unless you control no Clues at the beginning of your end step, and the ability will do nothing if you control a Clue by the time it resolves
Two mana to flicker a creature or artifact isnt the best rate, but when you can flicker many targets at once, you have a powerful tool at your disposal
Teferi, Temporal Archmage, the Blue card of the cycle, offers the standard card draw and can untap permanents
It finds most play in decks expecting to have lots of mana spare or with cards such as Aether Vial but mostly it gets played in the most limited of formates like sealed deck where it is highly splashable and becomes top quality filler
Venat, Heart of Hydaelyn gives you more card draw in your Legendary Matters decks, lower down on the curve
Ryan: This is a solid green creature, but I'm just not super sure where it'll fit in Standard