Level 5: Harden, reduces damage taken by you hero by 50% for a duration.

Level 15+IP expense: Darken, enemies lose their team sight temporarily, and can only see what their hero sees.
The game also ceases giving them automatic notifications.
They may still talk to each other however.


Anyone else have ideas for summoner skills?

Harden isn't a good name for a summoner spell. Just throwing that out there now.

Darken is OP I know one of the charachters in HoN has something like that, but it's way to powerfull of an ability for a well organized team and should not be implemented in any shape or form. The abillity to gank freely and take towers with out the other team even knowing is so strong that unless you want to see it on 10 out of 10 heroes every game it shouldn't be part of LoL.

Any blind time is enough for the entire team to shift position on the map. If you want to kill a lane and it only lasts 1 second that means five seconds for a team to form up, which is plenty to get the jump.
This skill's greatest use is not backdooring, so much of winning and loosing is possitioning and surprising the enemy team that you just couldn't affoard to not have the skill while playing against a team that was using it.