Zilean in URF/ARURF
The bomb timer on Zilean's Q remains at its default 3 second duration on URF modes. This, combined with his high default CDs, makes his bombs extremely unsatisfying to use, as they are not spammable (even at max rank, only barely spammable), they are extremely hard to hit (with all the movespeed buffs and low-CD dashes/flashes), and they take 3 seconds to detonate (wayyyy longer than other URF damaging abilities).
I think giving the detonation timer a lower fuse is necessary, as Zilean is currently extremely unsatisfyingly slow on URF. Perhaps the 80% reduction is too high (.6 second fuse makes the double bomb interaction window very narrow), but it definitely needs to be narrower.