Made this list after learning that a rioter is fixing some of Nunu's bugs. Not sure if they know about these (hem hem they're in public view on the wiki hem hem), but worth a try to make this champ greater than it is already. I've divided them based on 100% clear bugs, stuff that is not told in the tooltip and may or may not be a bug, and simple inconsistencies.
1. Nunu's passive cleave damage will critically strike when the basic attack does, but it will not deal any bonus damage. This is probably unintended because, other than benefiting from Infinity Edge's critical damage conversion (nunu ad?), it's useless to have it crit.
9. If Nunu's W snowball is created on top of minions / small monsters, these are instantly dealt maximum trample damage (60 / 75 / 90 / 105 / 120 (+ 100% AP))
11. The tooltip says that Nunu's W knock up increases based on the size of the snowball. That's not true. The knock up is static at 0.25 seconds. What increases based on size is the stun which is 0.75 - 1.5 seconds
14. If Nunu's W snowball is released before 2.5 seconds, its size will reset. Knowing that the snowball will roll longer based on it size, this time is static at about 1.4 seconds if the snowball is released before 2.5 seconds.
2. You know the cool animation nunu does when killing small/medium minions/monsters with Q? If you go spell vamp (some people, including me, probably do) , doing this particular animation will make Nunu heal less (Q should still heal the same) because other than making that cool animation, minions will be dealt their current health in true damage which is lower than your q's true damage (to do that animation, q must be able to kill the target first). The animation is cool and all, but who would've thought that killing a minion with q heals less than killing a monster with it.
3. Nunu's W lasts for 10 seconds but only increases in power in the first 5 seconds.
4. Nunu's W slows him by 50% for 1 second after he casts it.
5. Nunu's W makes Nunu immune to slows for the duration.
8. The tooltip in game only talks about explosion damage, but it totally forgot about the damage small minions and monsters take on the way, which is different from the explosion damage.
The explosion goes from 36 / 45 / 54 / 63 / 72 (+ 30% AP) to 180 / 225 / 270 / 315 / 360 (+ 150% AP)
The trample damage goes from 12 / 15 / 18 / 21 / 24 (+ 60% AP) to 60 / 75 / 90 / 105 / 120 (+ 100% AP)
10. The snowball also explodes when colliding with champion summoned units (zyra plants, heimer turrets etc..) and medium monsters. The tooltip only mentions champions, terrain and large monsters
12. Both the damage as the stun don't change in the first second.
13. After releasing the snowball, it will explode when encountering any unit (minions and small monsters included)
17. Enemies hit by Nunu's R will remain slowed up to 3 seconds once the ability ends.
6. Nunu's W doesn't give him bonus movement speed instantly. After lots of tests i found an approximated formula:
(X / 100) - Y, where:
X = Total Flat MS after caps
Y = 0.1 per 1% %MS
All these numbers basically mean that Flat Bonus MS increases the time it takes Nunu to start getting bonus ms while % Bonus MS decreases it. Having enough flat bonus ms will make Nunu not get any speed from his W for the entire duration.
7. His maximum reachable movement speed during W is based on the higher value between his Total MS + 85 and his Uncapped Flat MS + 85 the moment he started his W. (check the wiki on how movement speed gets capped)
15. Nunu's W lasts for 10 seconds, so it's not based on units travelled but on time channelled. Problem is, he still has a cast range. A cast range will basically make you walk closer to where your mouse was when you pressed the ability, before the ability actually starts. (i.e Casting W closer to you from the intended reachable location, will make you arrive faster to that location than casting W directly on that location)
16. When using E about at the end of its cast time, it is possible for Willump's Turn to come in while Nunu is still launching snowballs, thus allowing snowballs that are about to hit the enemy to not benefit from Willump's Turn. This is more of a thematic problem because i don't believe Nunu and Willump could be desynchronized.
Please tell me what you think about these, and if you think something i said is wrong / not true.