Tbh it's not bad on champs that are mages who exploit auto attacks somewhere in their kit, especially with Transcendence.
Ones I run it on:
Karma specifically it's good for "training" you to use her passive correctly; Hit multiple champs with her Q, and then also follow up with an iceborne auto, and they Ult will almost immediately reset. It helps get you out of the habit of ignoring that part of her kit, and just spamming Q on spells for lower average damage. It also helps get to that point of the game where Karma no longer loses CS faster, since Iceborne is a third aoe hit which is just neat for wave cleanups.
It's also surprisingly better on Sona and Nidalee than a Lich bane in many occasions, because a Sona that is even remotely tanky and has on hit slows just creates a situation like Nasus: They can't run from you, and you can chase them forever, while you have enough self sustain that you'll also very rarely die, because the Shields and Heals are large enough to survive any non dive damage.
Nidalee seems counter-intuitive, but a 20% CDR aoe proc on her Q hit or Lunge = a much more reliable reset on her abilities by killing a mark instead of sometimes missing them. Furthermore, ALL sheens work the same on Nidalee; They all translate into magic damage, and the only difference is by what magnitude (Lich is Base AD + 75% AP to one target, Iceborne is double, Trinity is Triple)
Her Q damage also scales to % missing HP of her targets, so she really doesn't need AP vs a low HP target. If you're vs Tanks, Iceborne is extremely viable, because you can go through 2-3 chains of Nid's skills and just wear them down, and you'll always win the exchange, because it's a tank vs tank fight, where the Tank Nidalee does increasing damage every time she Q's as the other tank's HP dwindles.
Nami's super situational in Season 8. I don't do it much in Season 8, because she lost her scaling Armor/resist from the old Resolve Tree in the most optimal new run combos. IG in Season 7 was like 160 Armor with base + IG as one item. Season 8 is like 132 Armor, so there's a pretty big difference in tank utility there. Still..... iceborne can help her play vs like an Ezreal.
MF is kind of a wierd Animal. She's one of the only champs who can pretty much build anything, and her Passive counts as both a proc and activator for IG. If building her as a support build, or even as an adc, often 
is viable, simply because of that fact (sheens proc on her passive, and second tap of Q). Sometimes it combines really well with her W to create Vayne like situations where you zone your opponent, while doing substantial damage, and while preventing them from running. Really nasty when combined with Comet.
