Since the LoL wiki does not say the spear stacks refresh on a target, I assume they do not, but a lot of people are suggesting that Kalista's Rend should have a 10 spear cap against monsters. Since each spear only exists for 4 seconds, the 10 spear cap is essentially meaningless unless new spears refresh old ones (you would need +2.5 attack speed for it to make sense otherwise).
So are old spears are refreshed by new spears?
The Chin2 votesyea... they keep stacking until you stop hitting them. Or until you press E.
Tis a nice day1 votesAll stacks of Rend spears fade only 4 seconds after the last application of Rend spear.
Sirsir1 votesYeah, they ALL fade after the LAST spear... Its a stacking debuff.
SouL1ess1 votesAll stacks of Rend spears fade only 4 seconds after the last application of Rend spear.
Tis a nice day1 votes[{quoted}](name=Axel DC,realm=NA,application-id=3ErqAdtq,discussion-id=zqpEeL6s,comment-id=0000,timestamp=2015-02-27T21:19:20.785+0000)
yea... they keep stacking until you stop hitting them. Or until you press E.