i vote both cata and magnus! i know a lot of people hate cata but its so fun to use and heres a tip..................
when a recon is shot with a cata charge the invisble skill of the recon will be useless cause even they go invisible theres a cata bullet rotating on them
so kill the recon while the cata bullet rotates.
Have you ever actually used a Catalyzer in Lockdown? The explosions just don't work. And sure, you could tag a recon to keep them visible but it's not like they'll depend on their cloak anymore. If you do actually succeed, it's rather probable that could've just killed them in the same amount of time as it took to mark them, unless you marked them with your first bullet.