Here are some things that I think would make Necro a brilliant class. These are all new ideas and of course assume that broken skills would be fixed as well.
1. Remove bleeds as the focus of the class. Between the cap and the rules for bleed stacking (new pushes off old), it’s too crowded for the class to shine.
2. Change Necro mechanics to focus on the more unusual conditions, for example Poison, Chill, etc.
3. I would LOVE to see Necros add new “sub-abilities” to conditions that enhance them. Basically, take the concept of Plague Form and make it into a theme. Necros could spec into auras that might, for example, add damage to the Cripple condition, allow Poison to stack intensity, add Blind to Weakness, etc. This would make every party appreciate having a Necro because they can objectively improve the group’s performance. Now THAT is a true “master of conditions”. Also, see #4.
4. Minions need to add something to group play. For example, the Flesh Golem could add 1 stack of Might to the group, duration 8 seconds, every time it attacks. Chaos monster (the one with the Blind ability) could add “25% chance to cause Blindness on critical hit” to everyone in the party. Bone minions could grant regeneration to the group when they die. Another angle on this is that certain traits could add conditions to the minions’ attacks; for example, all minions inflict 5s of vulnerability on each attack, all minions inflict 1s of Cripple when they attack, etc.
5. Just a thought – add an ability like “Reinforcement At Hand” , a grandmaster trait, that is something like “all minions will reanimate 5 seconds after dying without being recast.” This would help with minions v. aoe. For example, if you have a minion master Necro v. Lt Kohler in AC, every few seconds all his minions go boom and then most of his traits are wasted for 20-60s. Alternately, GM trait where minion cooldowns start ticking at the time that the minion is cast, not after it dies.
6. Add a cleave melee weapon, probably Axe. While Axe’s auto-attack deals very little damage, if it dealt an AoE weakness then it would be a strong addition to the group and would encourage a Necro to use a range that isn’t used by many classes and rarely offers enough to come closer than 1200.
7. Improve Necros ability to slowly regain life. It’s very hard to win a war of attrition without the ability to sustain. The siphon idea is ok because it isn’t burst healing, so it’s attrition style, slowly refilling. This could even apply group wide, for example a Life magic GM trait that reads "Allies receive a small heal (100pts) when applying a condition (1s internal cooldown – no 1k heals for “On My Mark”).