Like a platinium main Skarner, I can say that Skarner is in a "balanced" state, right now the jungle"tank" Skarner its strong, and this is in great part by: 
combined with the 25% bonus health of Cinderhulk and the strong engage active part, make Skarner a true nightmare, he can easily run with W and
to catch a key target with Impale, his passive stack in AoE, so you can stun and damage targets at the same time also peeling your adc, honestly its a good passive and for me, its a very good passive to clear the jungle too, his old passive remains on his Q, so I don't know why you say that its no longer...
Finally his E recently received a dmg buff, its a utility skill, can be used to init the gank, peel your adc, disengage, if you land a good E, you can easily put a Q, and you only need a second Q to put the stun and then the kill, with
you can secure the kill. the % slow its strong and hit various targets.
A good build are:
or
,
,
+ Cinderhulk + Boots + MR item like
or
can be a good STANDARD build on him, you need a
early to solve the mana problems, and amp your dmg too.
Skarner its a strong pick and balanced IMO.