I tried to charm a Jax to see if I could one shot him, and he survived the combo, then flash + leaped me, and killed me. I was full build Eve, and he only had MR boots for MR. It wasn't till afterwards that I realized my noob mistake, I had forgotten about his R.
It's kind of annoying that some old champs have ults that have particle effects that are too similar to their basic abilities, or too simple or small of particle effects, making it easy to escape your notice. Jax can activate counter strike at the same time that he ults, to make his ult less noticeable, since the counter strike's effect looks similar in color, and makes it hard to see for anyone with poor eyesight, or who doesn't know exactly what Jax's ult looks like, or anyone not paying perfect attention.
There are a few champions that have ult effects which are easy to miss, here's my short list:
1) Jax (his ult can be partially concealed by his counter strike)
2) Mordekaiser (very difficult to see, it's easier to listen for his laugh, but not for the hearing impaired)
3) Veigar (might depend on his skin, but the projectile portion of his ult looks too much like his Q)
4) Trundle (his ult looks kind of like the active effect of Blade of the Ruined King, it's not enough)
I do wish Riot would give these champs a mini rework of their ult effects, so they would look a little less like basic abilities, look less like item actives, and overall just make them much more obvious and threatening in appearance.