Like most Magic: The Gathering cards, the value of Omen of the Sun depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Theros Beyond Death)
If you want to perform a character action that requires exerting the card (questing, challenging, and certain abilities), that card must have been in play since the start of the turn
But if you are eating during your upkeep it spits out a 1/1 Thopter just like the card it references
If you do, create a 3/3 colorless Construct artifact creature token named Boulder that's tapped and attacking
This card lets you mill your entire deck for just one mana by not playing any basic lands in your deck, setting up the perfect one-two punch with Laboratory Maniac
Disdainful Stroke Disdainful Stroke is a solid situational counter