If you have {yeva, natures herald} in play. Then play {yevas force Mage} and before it comes into play, play another creature and have yevas force Mage target that creature? I know this doesn't have many applications. Just wanting to know how flash creatures work
This is a stack understanding question.
On one side you have costs and conditions
In the middle you have the stack
On the other side you have resolutions
Instants and Flash dont care if things are on the stack already, if you pay their cost you can place them on the stack before other spells resolve.
Soulbond is a triggered ability that triggers off of entering the battlefield so until that condition is met it wont go on the stack. So as long as you get your other creature to enter before that trigger happens then yes you can soulbond to that new dude.
Thank you. Now to find an application that really leaves a bang
Ninjutsu cards?
Just a very minor detail that you might as well know: nature's herald does not make it so that all green creatures you cast have flash. You can choose tocast it at normal speed. Won't be too relevant but good to know.