Ares - You're right that FE has 3 targets on 2-distanced row ahead. Ares has 4 forward targets :). The advantage of L imo is that there are many more pieces able to defend themselves in straight line distance 2 (vs FE, so FE cannot just step into the square to threaten them), than vs L (Ares can step in and threaten them unchallenged). Needing kill for each magic certainly and significantly tones the magic use down.

Cancer:

• Displacement immunity on Phalanx is disadvantage, I'm not sure why you list it otherwise :) . You can't swap / push it for bigger move / step than 1 (own movement speed, err, I mean slowness).
• Phalanx has better attack, but how many turns you usually need to take with it, before it can attack (as either good trade, or 2-kill threat thx to block) ? Cancer can move once , and already threaten 2-kills starting next turn, higher tempo on the threat.
• Pike's ability is nice, but only after Phalanx fullfills his purpose, or takes 1st target before dying to use Pike. You don't put Phalanx out just to be taken by those examples, without anything else. Again, it takes lot of time for Phalanx to get to killing, which also means Pike's ability. Moreover, thanks to that slowness, unblockable defenders have much easier time keeping up with Phalanx (circling around, trying to find a spot to break through). Defense is harder against Cancer - you might need better mobility on counters, or more of them to cover bigger area.
• And - the armor removed only by 1 square - if Phalanx breaks in, you know that 1st regular melee would be sacrifice for taking out armor, and 2nd can kill him. With Cancer (++ or +++), 1st attack is sacrifice, 2nd attack is 88 % sacrifice, 3rd attack is 75 % sacrifice, ... purely as math calculation, that is average of 3.6 sacrifices, before armor is gone completely :) . As situation within game, Phalanx (or all-round armor in general) is so strong, just because of that 1 sacrifice needed, if counter isn't present. Power = kills[1 -> 2 ]. For Cancer, how better is Power = kills[1 -> 2 (in same situation as Phalanx) -> 3 with real chance -> already game over :) ] ?

Pisces - If I understand it correctly, the splash also comes from icicle, so it can combo / chain itself (if there are targets continually next to each other), and keeps killing units each turn, which maybe are even further away from where the first push happened. Uff, freeze theme was just a frosting on the cake, its a machine-gun with range growth :) .

Virgo - What I mean:

Virgo can alone get next to King, for King to kill him, and the other ally of Virgo retakes King. Yes, magic / ranged champions can stop him, minions can too. But said from other POV / side - no amount of melee champions can stop him - seems as very strong King threat, among the best in-game, for pretty low cost.