I suppose so but it's during the day and wouldn't it take some time to actually set off to it's full effect? Wouldn't that put a lot of pressure on archer? It's all on you two how you want to do this. While Misty Metro would definitely help get you away it could leave archer in an area surrounded by assassin, and a guy who's already invisible to most people due to one of his skills/NP's. In other words it should be a coordinated effort unless you flat out leave assassin to the dogs. Or Lancer comes into save your candy asses.
Spirit forms do exist, for this reason, furthermore, you got stuff like summoning a servant from a fair distance.
Unless I am sorely mistaken this is a common thing with command seals.
(for reference about 1:42)
Edit: And Darkened Misty metro takes seconds to expand outwards. Its less of the speed to setup and more on how long Taka can keep it up with her mana reserves already quite drained from leaving Jack in presence concealment.
