ok, I fumbled a bit with the mod fusion. what I can tell is this : every mod is "level 0" (even if it costs 4 points to put it on a weapon). the level is indicated on each mod by looking at the number of white horizontal bars there are on its left side.
fusion is used to level up a mod, making it more and more cost efficient, especially if you can put it in the correct "pattern" (dividing its cost by 2)
when fusing, you can see a vertical bar on the left of the card. it's the "XP" bar of the mod. once it's full, the mod levels up. the XP bar fills relatively to the elements used for the fusion :
fusion cores give more or less XP accoridng to their rarity (uncommon 1 gives few, but RARE 5 gives a lot). you may need more than 1 fusion core to level up a mod.
However, you can use duplicates of the mod (say if you have 4 times the same mod). This is much more efficient, as one duplicate will give a boost equal to a RARE 4 fusion core. basically, if you have 2 times a mod, you can turn them into 1 card which is one level higher without using fusion cores. this doubles the efficiency of the mod for costing only 1 more.
you can then use a mix of duplicates and fusion cores to level up a mod.
nothing stops you from using other non-related mods to fuse, but the XP added is really low.
am I right, slainchild ?
