Dont have it on steam but because of the statistics and achievements, thinking about buying it on steam.
If i have D4 here, do I need to buy only DLC on steam or both?
Different platform. Buy both. But to get your “stuff” link your BNet to Steam so when you use Steam, you still get your same account.
If i wanted to i could buy on Steam and bypass the Bnet launcher app. Ridiculous queues when servers are having problem. Never seen the queue thing on Xbox consoles except for the beta testing they did before launch.
DISCLAIMER
I will not be responsible for bad account linking. Research that on your own. Because it takes 1 year to “reset” it.