This is my [Harrow] build! It is great in most situations and is very flexible.

For some reason on this site, people are using [Redirection] for more shields but all that does is increase the duration of the second ability. With this build I can get it to last 95+ seconds which is more than enough time.

If you want, you can do two more forma to slot something like [Primed Sure Footed] in the exilus but it's not required to do well with this build.

You can swap out [Rolling Guard] for something, since you have on demand shields anyway. If you are just picking up [Harrow] now, I would try to keep it in though, at least while you're learning.

Because [Harrow] focuses on crits and headshots, make sure to build your weapons around these factors too. I personally use the incarnon [Dual Toxocyst] (with secondary outburst and [Ceramic Dagger]) but there are lots of other weapons to experiment with like [Sporothrix], [Burston] incarnon, [Zymos], [Stahlta] etc. It mostly comes down to finding a weapon you're comfortable with that synergises with more firerate and crit. Because I like the [Dual Toxocyst], I use arcane precision, but if you choose to use a primary make sure to use something more relevent(arachne, acceleration etc).

Archon shards: 3 casting speed shards(or 2 tauforged), otherwise you will need to slot in [Natural Talent] for [Augur Reach] and add another forma. For the other slots, I use red shards with secondary crit, but you could do ability strength or quality of life.

For focus school, you can branch out from zenurik since harrows energy generation is insane. I like madurai and vazarin.