A list of Champions whos' ults cost more than 100 mana and why

Amumu (100 / 150 / 200) ---> huge teamfighting ability and very potent. Land a good 'mumu ult and you win the game, justified Draven (120 / 120 / 120) --> Probably due to the fact that it comes back to Draven Jarvan IV (100 / 125 / 150) -----> Idk why, walls are breakable and easily escaped; probably because it "traps" people? Karthus (150 / 175 / 200) ---> pretty obvious Oriana (100 / 125 / 150) ---> potent teamfighting ability and potential gamechanger Pantheon (125 / 125 / 125) -----> mandrops require more energy (pseudo global presence w/ dmg) Singed (150 / 150 / 150) ----> honestly no clue here Skarner (100 / 125 / 150) ----> point and click hard cc that drags you into enemy team Sona (100 / 150 / 200) ----> My guess is because of its potential... even though 200 mana seems like a bit much IMO Teemo (75 / 100 / 125) ----> 1 free ward every few seconds that lasts way longer than a regular ward Twisted Fate (150 / 125 / 100) ----> obvious Twitch (100 / 125 / 150) ---> probably the team fighting potential of melting teams instantly Veigar (125 / 125 / 125) ----> ??? no clue here (fun fact, Veigar's ult cost on release was 400 mana) Vi (100 / 125 / 150) ----> point and click uninterruptable hard cc Warwick (100 / 125 / 150) ----> see above (minus the uninterruptable part) Zilean (125 / 150 / 175) ----> brings someone to life Zyra (100 / 120 / 140) -----> huge aoe teamfighting ability

A good number of these could be standardized. What do you guys think?