A subtle card and not quite as bad as it may first look. Mirāju may have strength 0 but it's value is not in stopping the runner through subs but in taxing the runner.
Essentially Mirāju is a question: runner, do you prefer the corp to optionally draw a card and (not optionally) shuffle a card from HQ into R&D or would you like to end the run? It doesn't say this on the card, but in effect running on archives is as good as ending the run (except if the runner wants to run on archives).
Unlike most ice the sub on Mirāju is likely to be broken only once: when it's rezzed the first time. Since breaking the sub means not getting into the desired server (or in the case of Mirāju on archives being bounced back to the outermost piece of ice) a runner, broadly speaking, has three choices:
- Accept that the corp gets to draw and shuffle a card back in. In the case of Mirāju on HQ that probably means lowering the agenda density of HQ significantly.
- Try to make the corp too poor to rerez Mirāju and then run twice, once to break the sub and derez Mirāju and once to get through it.
- Kill Mirāju. While this is easy with cutlery or parasites it does waste a kill card on a low cost piece of ice.
With most code gate breakers breaking Mirāju, and thus derezzing it, costs a credit and a click. It costs 2 credits to rez Mirāju. Since a click is worth more than a credit derezzing Mirāju costs more than rezzing it. If the runner has a money advantage that's not necessarily a problem, though it still costs clicks and that may hurt more than the credits.
This calculation assumes however that there's no rezzed ice in front of Mirāju. If there is the story changes a lot. Assuming there's one piece of ice in front of Mirāju that takes 2 credits to get through the runner needs to spend 3 credits and a click to derez Mirāju vs the corp's 2 credits to rez it.
It may be more appealing to the runner to let the sub fire. This however gives a huge advantage to the corp if done regularly.
When building a deck around Mirāju be aware that there's synergy between Mirāju and Chief Slee that makes runner through Mirāju regularly a really bad idea. Especially in a kill oriented deck this is a scary combination.
Mirāju does have some downsides to the corp. It can be difficult to keep rezzed if the runner is willing to break it repeatedly, those 2 credits per rez do add up And the second clause of the sub is unconditional, if the runner runs through Mirāju the corp has to shuffle a card from HQ back into R&D, even if it would mess up their plans.
By the way if you're thinking of slapping a Sub Boost on Mirāju, that won't work. The special ability only works on the printed sub, not all subs.
Overall Mirāju is a good cheap piece of ice for gaining an advantage through the actions of the runner and deterring all too aggressive running.