I can't believe that the people here do not understand the concept of a template... If one has multiple of the same kind of creature and all are healthy, then any of that creature type can fill that slot in the template.
We all use templates. It works like, "Yeah, I had two dark archers doing weakening, one barren healer, etc." It's not a hard concept people.
In the real world and in Magic Duel we learn by creating and amending just these sort of templates. Think about the mental process you go through when creating new rituals or recreating old ones. It's all about memory and templates. There is no reason why the UI cannot aid rather than hamper the process other than our own limited vision. As so much of the came centers around rituals and their maintenance, it is sad that this UI is about the poorest in the game.
There is no reason why one should not be able to devise and set a defense (or attack) ritual while in sanctuary. In a "real" Magic Duel world or in the real world, this is what each and every one of us would do. In the real world we work on our rituals both in sanctuary and in the field. That Magic Duel does not have an interface that allows us to work on rituals at any time other than when we are jeopardy is a failing, not a feature.
The interface for devising and discarding rituals should be available at any time. The only thing keeping things as they are is linkage between the interface for selecting an attack ritual and the interface for creating a ritual. They are separate actions. As every ritual MUST (at present) be bound to a name, there is no reason why one interface could not manage rituals while another would select an existing ritual to use for attack. Of course, the attack interface could still provide the capabilities of ritual maintenance.
As a programmer with almost four decades of experience I see no problems in implementing such interfaces.