Okay real crude 10 minute pitch. This is super nerdy. I AM NOT A WRITER. Also most of these skills are probably bad. Also this may not actually be an assassin.
Blair, of the Ruby Vanguard
Blair is a young demacian woman who is not as she seems. Inducted into the highest ranks of the royal army at an early age, many were astounded by her swift rise through the ranks and downright stunned when she was appointed to the Ruby Vanguard, the crown's elite assassination unit, tasked with eliminating enemy commanders before a battle even began. Only the crown and other members of the Ruby Vanguard know Blair for what she truely is, a host, bound by sorcery and united under a single conscience.
P - Resuscitate (This is a fun mechanic I've been playing around with, seems like it would fit an insect theme) Blair can right-click nearby corpses (minions or champions) to dissolve into a cloud of insects and teleport to them, consuming the corpse and healing herself. This can be cast after death on champion corpses to revive herself Q - Barrage of Stingers -On an Ammo System, has 3 charges -Blair fires off an insect missile that deals damage to the first target hit and applies a stack of "weakness" to them. -Blair's attacks gain X AD per stack of weakness on their target. W - Consuming swarm -Pure Passive - Every third attack or spell on an enemy champion afflicts them with Consuming Swarm, consuming swarm stacks infinitinely, and after 3 seconds of not being applied will detonate, dealing X damage per stack and healing Blair for Y E - Cloud of Pain - Blair dissolves into a cloud of insects, becoming untargetable and dashing to the target location over .5 seconds. Any enemies along the travel path take X damage. R - Assault of the Ruby Vanguard (I've always wanted to do this ability for an assassin) Blair attaches insect swarms to all nearby allies, allowing them to apply W - Consuming Swarm to enemies for the next 15 seconds. R can be recast during this time to allow Blair to globally teleport to any enemy afflicted by Consuming Swarm.