Kingdom Hearts II - The second Demyx fight. God damn water clones.
Triangle is your friend. Wild Dance should take out all but one or two, then you can just mop it up with a bit of Thunder.
Back on topic, the mission in C&C4 where you have to down Colonel James' GST as it passes overhead. Practically the only effective way to win is to start out as Offense, and take out all the Crawlers and at least three of the AA turrets. Then you have to switch to Defense and build up Laser units and defensive structures, with Rocket reinforcement to handle the incoming aircraft (since Viper Turrets can't target air). Even with this, it's more a matter of luck than anything, since another Crawler will appear somewhere on the map once the GST arrives proper, and if you don't deal with that too, you get inundated with tanks, Wolves, and once, I even had to deal with
two Mammoth Tanks.
Did I mention the GST has 30000 HP (which a Crawler is a minuscule fraction of - and those take
forever to kill normally) of which you need to deal
95% in damage to; if you don't play at least Skirmishes, you're basically stuck with weaker Type I units when the GDI Crawlers are at least Type II (meaning even their Crawlers fight), and even possibly Type III (due to the Mammoth Tanks);
and you're timed?