You won't get agro from hellion if you attack, especially if you have Master Summoner rubies, but late in game you gonna need to party, just get a guild and make some friends, going solo is harder.
Also, I know there are lots of guides out there and the "how do I build" question gets asked way too much, but I'm having a real hard time getting all I want on my summy. Do I need blood injection to be a decent healer? Is dark pact really necessary? Both got the short end of the stick for me. I'd like something that can heal and dot well, it seems an either/or deal. Just 16 atm. Hellion 3 I need for making questing so much easier. Same for 3 decompose. I found 2 blood shield typically ensures I can cast if hellion dies and 2 fear helps ease cd enough for me to use it to safely get 2 kills at once.
For leveling you don't need blood injection, for full healer end game you do.
Dark pact in lvling at your lvl doesn't help, get it later.
Again at 16 you don't have many talent points and rubies, keep playing and you'll see summy heals and does alot of dmg, leveling is a joke as summy after lvl 20.
What are all the ways to get blood?
vampirism at you lvl, without dark leech rubies, later luker
Proficiency increases all damage no matter of it's type, for a build with hellion and lurker check the other threads.