Verb (5-dan, む, transitive)
1. to step into (e.g. someone else's territory); to break into; to raid
こちらに踏み込んだ瞬間に、その魔法は発動した。The moment we stepped in here, that magic activated.
2. to come to grips with; to get to the core of
かなり踏み込んだ質問であることは承知している。I'm aware that this is a rather probing question.