The counter effect is reliable against a lot of different spells and costs only one mana
Jafar, Striking Illusionist is an Amethyst Ink, Floodborn card with much stronger stats than Ursula at first glance
(It is possible, though, to get commons and uncommons in other slots.) Traditionally, in a Draft Booster, you get ten commons and three uncommons
Despite this rather substantial drawback, Exploration is still an incredibly useful card
Indeed, only a few competitive staples are included here, meaning you will have to combine it with staples you already have to make it more competitively viable (more on that in my upgrade guide)
There are a few sets and planes that heavily feature ninjas, and a few one-off sets or ones with reprints