type -invokelist ingame to see his combos.
invoker can be played in many ways. if you max extort he has +63 damage by level 7. thats like a free relic.
He is a pretty difficult hero to play as he has no stat bonuses and his HP at level 25 is around 1200.
But on the right hands he can be deadly. max out wex and invoke and you get Alacrity which increases your IAS by 160% put that on your dps like troll/ nevermore or even tiny OMG.
apart from that theres QWE invoke which gives a mini silence and blast ppl back which can screw upchannelling spells
EEW i think is chaos metoer if you have mass disablers in the team this is great.
Ghost walk slows all enemy units around and you are invisible kinda like omni but with invi.
Cold snap i think is QQQ which is great for ganking and can keep a unit perma stunned
Ice wall slows and deals a bit of damage.
Sun Strike is a global spell and can kill your chickens lol
finally theres cyclone
These spells look impressive but are mana intense and you need to max out Quas Wex and Extort to deal its full potential.
He can fit any role in your team but the point is can you play him according to the situtation?
In the hands of a pro he would be awesome and that too will take a few months to master the skills he brings to the table.