Many may argue or debate a few of these tiers but I will give my quick, detailed explanation of my approach to Kerrigan. Some builds work better with certain teams and maps, but this build works for many scenarios and owns 1 on 1. Since Kerrigan is a melee assassin and her trait is produced through basic attacks this Nexus Swarm build is one I created to maintain a shield around our self while attacking and grasping in enemy waves. Also splashing huge spikes of damage and slowing everything/everyone around us.
Level 1 can benefit from seasoned marksman as can for many toons, but Kerrigan will get her siege damage as she trudges along, she shouldn't have to focus on it. Her +20% on the Grasp is nice for Hero encounters as well as scraping in masses of minions for the Sweeep. She gets her Xp as well.
Level 4 Fury of the Swarm, think about that for a second. Basic attacks splash for 50% damage around Kerrigan. YES?!! Every pile of minions, group of mercenaries, waves of enemies and objective encounters my basic attacks splash around me! Sign me up three times... This is the Swarm part of our Nexus Swarm build. Our other part we get @ level 20. Should the enemy be so unfortunate. =X I can see people arguing envenom is better for the mage or hero build or even focused attacks being a better choice. I think we all need an ability to single target and group target to be really efficient if we are a damage class. For an auto attack build this talent is an easy choice for me.
Level 7 I think Battle Momentum suits her so well, especially this particular build. Her 3 skills are so quick, strong and offensive that this skill just makes her a force. Impaling Blades is such a great skill shot, but rather difficult sometimes as Kerrigan is such a frantic melee character. So I struggled many times trying to work in a talent for it. Its zoning and stun alone make it a huge part of her engagements. So in point as we auto attack we are reducing our 3 abilities by .5 seconds per attack. They will light up quicker and we will be stunning, grasping and ravaging more!
Level 10 Summon Ultralisk has become a slam dunk for many because of its ability to pursue. We all know how annoying Nazeebo and Jaina's familiars are correct? They're so strong even after we may bite the dust, by re-focusing them on targets that are low. You can summon the Ultralisk around corners, over walls, on top of objectives and on structures too. I can definitely see Maelstrom being a huge benefit for this exact build also =D but when we're talking PvP, 1 on 1 or CLutCh* I want that big gnarly beast chasing my enemy as he/she runs away with 1 1/2 bricks of Hp LoL!
Level 13 Double Strike is such a strong talent and compliments our whole build we have based our damage around. Next basic attack after ability +50% damage. Our battle momentum is already making our skills Cd quicker and our Nexus Swarm build just spawns off our auto attack 'Assimilation Shields'. So as you attack you are also making your talents proc ( fury of the swarm, battle momentum & 'later' nexus blades =p ) Every time you strike an enemy with a skill, next basic attack +50% damage makes Kerrigan even more of a force 1 on 1 or pushing as a group. Now @ Level 16 we will take a survivability talent, so I know many would argue Sprint is a better choice here. Well this isn't a pop and poke or run and gun build. We plan to destroy everything in our path or die trying to protect our friends not running away every time we are low.
Level 16 Aggresive Defense is Kerrigan's ability to maintain a shield around herself to ward of some damage as it comes her way. Assimilation Shields earned from basic attacks and abilities increased by 100%. This makes our trait we have that accrues as we basic attack double in power. Why not make her only defensive skill, especially since it is passive and has to be produced through basic attacks, twice as large around her. Sounds like it also just fits directly in line with our current Nexus Swarm build. As long as we are auto attacking our basic attacks produce and maintain a shield around us twice as strong as it would be while we are splashing enemies around us and scraping in waves of kills.
Level 20 Nexus Blades basic attacks deal 20% more damage and slow the target for 1 second. So our build has just got an upgrade of epic proportion. Our auto attacks splashing around us are stronger and also slowing waves around us. We are slowing the enemies around us and producing shields and splashing them with spikes of damage. This is the Nexus Swarm. If you find yourself in trouble try to Ravage to an enemy target for mobility out of a jam or drop an impaling blades at a hostile choke point to mount up and dip. If you have support near you or see minions in a wave just start slicing and dicing and you vortex damage and shields all around you. I know a second Ultralisk would be nice, and many builds benefit from a perfect Bolt of the Storm but Nexus Blades is one of those Uber 20 skills you can really spawn off of. Good Luck and Have Fun* Sorry this is my 1st post and it might not be the best but it was from the top of my head while Ravaging this afternoon. Thanx and Slay Away!!