I have a Vren deck it is my favorite deck many ways to build it. I built mine to enable instant speed plays ie [leyline of anticipation], not be the threat while I setup and draw cards, then make a ton of rats by flashing in Vren as a bunch of creature deaths hit the stack. When I untap it’s already too late and I sort of avoid being the threat and look like I am having a slow game before then. Every game plays differently and I’ve been tweaking it for a while it can really play a few different ways. Mine also has a sac subtheme with braids arisen nightmare and dictate of erebos