Root or enstill ?

[isoka]

You are better using root at least till you hit 27 where your enstill will be double root duration. Before that, it costs twice the mana of root for poor duration extension with the risk of breaking it early if nuking.

Once you hit 29 and you get your AoE snare spell, you will most likely be quadding when soloing instead of root/nuking, at which point your root will most likely become a crowd control spell for which you will want your highest level root (longest duration).