What you can't see is so OP

is a champion I've always known was really strong. Back when I main'd Shyvana top he was the one champ I was always afraid to see and demanded I take Ignite so I wouldn't be ran over in lane. Despite that I never really played him and as my main roles switched to jungle and support I thought about him less and less. With the small bump in popularity Trundle got when he was used as a support in the LCS and Challenger scenes I figured I'd finally try him out (I'd owned him for years and never played him).

He quickly became one of my favorite picks to take support and jungle and after a bit of farming I can face-roll out damage while just stacking HP. At this point I can say beyond any shadow of doubt that the things that make Trundle strong are the unfair amount of hidden stats his abilties come with.

Passive - King's Tribute - Trundle heals for a percent of the max health every time an enemy dies in range.

I always knew that Trundle healed for a crazy amount, I just didn't know it came from his pseudo Cho Gath passive. This one isn't so bad, it's just not immediately obvious the way it is with Cho, who gets a small particle every time he kills something. The fact that Trundle doesn't even have to be the one to kill it seems unfair to me but I'll leave it at that. The passive healing is hidden.

Q - Chomp - Auto attack augment, deals bonus damage, slows, steals attack damage from the target, gives double the AD stolen to Trundle.

Holy cow that's a ton of stuff going on for that short cool down ability. I suspect this ability is the biggest offender for people taking bad engagments on Trundle (they do it all the time too, I've killed so many people for diving on me because I'm "support" Trundle). The bonus damage is simple enough and the slow is obvious, but wow, the AD stealing, that lasts four times longer than the slow (8 seconds), with no animation, is a huge deal. At rank 5 it steals 20 AD and gives Trundle 40 AD. The stolen AD is hidden.

W - Frozen Domain - Bonus movement speed and attack speed, bonus healing from all sources.

Another one where the bonus move/attack speed are obvious. Look Trundle moving on the ice is so fast, and attacks way faster, wow. That's no big deal; it's the hidden bonus healing that isn't made obvious. We're already encouraged not to fight Trundle in his domain but sometimes players will pick bad fights thinking they can out burst Trundle's dps. Hidden healing is hidden.

E - Pillar of Ice - It's a pillar, it slows, most obvious ability is most obvious.

R - Subjugate - Drains life from target and steals 20% of their armor and magic resist

This one I'm on the fence about. As someone who was around for the Trundle update highlight, I already knew that his ult stole armor and mag resist. A new player though, would probably be less likely to know and may end up wondering why he's suddenly so much squishier. The animation and healing life are obvious enough and I can't really think of a way to show that armor and magic resist have been reduced/increased but still; hidden stat changes are hidden.

All in all, I'm pretty sure that Trundle is the champ with the most hidden stats/utility in his abilities of any champ in the game currently. I personally really like Trundle atm (though forcing opponents to take Ignite to not lose lane may be a bit OP) but I feel that a lot of his abilities need additional particles and animations to show both allies and opponents when a lot of these stat changes are happening.