Archon Demetrius's Riad (2k)

Hello guys this is my new army list I been playing for about a week and a half but I still don't know how to use reavers properly. Either I use them too early or I they get assualted after I bladvanes them.

This is my list:

Archon w/ VB HB SF CD ST HWG
Haemii w/ VB SS
7 hwg wytches hekatrix w/ agoniser PGL
Raider w/ ES NS FF DL

2x 3 trueborn w/ 2 SC
Venom w/ 2x SC FF

3 blastborn
Venoms/ 2xSC FF

3x 10 warriors
Raider DL FF NS

2x 4 HWG wytchs hekatrix w/ VB
Venom w/ 2 SC FF

2x 6 reavers w/ 2 HL


I so far won against Crimson Fist player(heavy droppod list with TLmetas and flamers) a eldar player ( had dawn of war deployment and I stole I, but lost to a blood angels player ( failed alot of my assualts due to his tanks being behind barricades )

But I want to get better with reavers any suggestions guys.