axiom schema of replacement

\begin{align*} \forall x \forall y \forall z( \phi \land \phi_y[z] \Rightarrow y = z) \Rightarrow \forall u\exists v \forall w(w \in v \Leftrightarrow \existst(t \in u \land \phi_{x,y}[t,w])) \end{align*}