Warhammer 40k: Blood & Iron updated to version 1.2115
-included a config for optifine that doesn't set everything to MAXIMUM OVERDRIVE
Type in the modpack name (Warhammer 40k: Blood & Iron) or paste the following url into the search box.
Finally, click Install at the bottom right of the launcher after you select Warhammer 40k: Blood & Iron from the list on the left. The launcher will handle everything else!