Planeswalker

[An Angry Fatman]

2 {Oath of Gideon} on the field and plays {Vraska the Unseen}. Comes into play with 7 counters and he tries to Ultimate Vraska, do I have an opportunity to {Lightning Bolt} before he can activate?

[Prplprince]

First all the Oaths are legendary so there couldn't be two but in theory if {Mirror Gallery} was out and  it happened I believe you do not have an opportunity to cast the bolt. You could only respond to the abilities activation. 

[imFourth of Phils]

maybe {Doubling Season} then ult, but you cannot do any response after a planeswalker enters the battlefield

unless you counter that spell or he done something, like casting another spell after playing it, then opponent lately or forgot to use the ability of planeswalker and uses it, then there is the time you can response

its about passing the priority

[Kaylesh]

FourthofPhils hits it spot on. Once a spell resolves, the active player gets priority. In this case, the player casting Vraska. He can then activate her ultimate before you get priority to do something. If he puts anything else on the stack, you get priority before that resolves, allowing you to bolt Vraska in response.

[An Angry Fatman]

Haha, didn't even catch that. A friend asked me to post that, and didn't realize that the oaths were legendary. LMAO

[An Angry Fatman]

Thanks for the responses! That's what I was thinking but I was having trouble explaining that. I guess I need to understand priority more :/