At lvl 1 you skill Q and last hit or push the wave then at lvl 2 wether W for healing and passive Q farming or E for melee and agressive way. At lvl 3 you can use E (Tunnel) to engage and do a Auto attack Qaa Qaa Qaa and then followed up by E for true dmg. At lvl 6 you can do the same Combo but to finish off 1/5 hp enemy with your R. You can also create tunnels behind you if you push a lot because when the junglers Comes you can run away trough your tunnels. Create tunnels when you recall in base so you can use them te get faster back to lane. Also if they have a squishy jungler you can check their jungle with your Underground but only if your lane is pushed.