For a lot of players who have been waiting enhancing their Professor X's, Cyclops', and Psylocke's this will help them rise to the top. Not only do they have finished high level bonus damage cards, but they will also be doing almost double damage on top of it.
Purple Shards offer some extra prizes that the other shards don't as well. Not only is there now a chance for a full personal power pack to drop, but there is also a chance for Ultimate Card Pack tickets, SR Ultron, and SSR Annihilus.
How to maximize now?
When I get an enraged boss I damage him down to just over half way, then I share him. The enraged boss will net team members 1.5x points, and it greatly increases my purple shards. If I'm able to get purple shard bonuses from two enraged bosses for the attack power I would spend on one by sharing it with my team, that's a win for all of us.
On the home stretch here, I would advise all players to share their enraged bosses once they hit 50%. The reason for this is because those purple shards are valuable and can get you additional power packs, and doing over 50% damage ensures you the star agent reward. Alliance members are highly likely to attack enraged bosses because of the double damage bonus and not getting charged the five attack points.
Attack your other bosses with a weak card and share them so players with no bosses up can attack them, otherwise, ignore them unless you're attack capped. The extra bonus from enraged makes them the bosses to target.
Good luck on the home stretch!