Diana is constantly changing what items she goes. The most common questions I get are "When do you go phase rush/conq over electrocute"
Instead of answering this 100 times I will provide a little insight on how I decide.
ELECTROCUTE : This rune page means that you are looking to WIN MIDLANE with early trades and push your laner out of the game. This rune page also means that enemy is squishy and you feel like you can 1v9 with assassin setup. If you are plat and under I would recommend almost always going electrocute and looking to push enemy mid out of the game and carry every single game solo. People in these elos will not punish you for going this setup and often not even build against it. You can push for early 2 and go q e second and all in with electrocute bait your q cooldown and re entry with qe and almost always it is a kill.
PHASE RUSH : This rune page feels much better for higher elos where a lot of the time enemy midlaner will not let you lane phase. You play for midgame where you get 2 item spike. Phase Rush allows you to avoid a lot of ganks because you can easily proc q e auto and run away at the speed of light. Often you are playing with your jungler and this playstyle is way less risk and much more reward. Most of your lane pressure goes away considering you do not have electrocute and abolute focus but it is much better midgame option. TP feels better in almost every high elo scenario as most midlaners will not let you lane. You are able to tp back for early base and play with team. Solokilling enemy mid is way less rewarding this season with the current meta benefiting hp and resistance stacking champions.
CONQ : This rune is good into health stacking champions and tanky matchups. I will take this into sylas, galio, a lot of other melee mid matchups. If enemy team doesnt have a bunch of cc you can opt for nashors second and get a lot of use out of the build. You are looking to trade around your conq stacks. You do not do a lot of all in dmg so please be aware this is a scaling setup!
