so if you have 2 items it makes a set. 

that would give you the 15% 

if you have 4 items that makes 2 sets, now you have 30% 

3 sets = 45% 

I hope that was answers your question. It's a bit difficult to explain it without showing. Pretty much the more sets you better your stacks are. 

so if you have 2 items it makes a set. 

that would give you the 15% 

if you have 4 items that makes 2 sets, now you have 30% 

3 sets = 45% 

I hope that was answers your question. It's a bit difficult to explain it without showing. Pretty much the more sets you better your stacks are. 

with that being said, yes the 15 should stack up. Just realized you said just 15 not the percent. 

How do you use battle coins

Can I ask if someone for  help? When deciding  what set of Artifacts should you choose for your champion, hiw do you match whuch is best for each champions affinity?