Ive been playin Tychus since November 2014 basically the idea is to empower the grenade.

If some one is hidden in the bushes you can take them out
If you have low life, you have life steal.
If Ilidian or Zeratul or any brusier is following you , you can throw them appart with your grenade and slow them while you use the machine gun. This also works if youre chasing anybody, they will run slow and you can push them back to you with the grenade range.

Also if youre under a bruiser attack , you can leave the drill in a bush and move around while using your Q

In the maps that i didnt pick , i would use FALSTAD instead