While I believe the surprise element was a major thing about Knight's Cover(it wasted a lot of turns), the main problem lied in the mentality of this game. First thing people heard was, summoners got more strudy, and with that it wasn't that they got too bulky to be killed, but people believed it would be easier to focus on chapions, instead or risking aoos in addition to their normal attacks, even with the powerful fireballs gone, the summoners are still extremly frail.
I do not want to give a spoiler example of the biggest move against summoners this game, so I will use smaller example. Thanks to teleport tactican, ipl nearly killed a summoner, after a single hit he was way down, imagine what if he tried to full attack! Now one thing I never got, why Raikage+AG didn't instakill ipl... All they needed was to eel Don then use AG's aura, no more aoo and sneak attacks on the summoner, that's an instant order(unless they champ aoos count as a supernatural ability, even then a 1v2 with the target being a the summoner is an easy one, especially if Raikage manages to stun). Fact is Knight would have been more useful if people actually tried to go for it, but the thing is, it's still weaker compared to most innates, with no active use. I'd rather have the ability remade to be honest, to some form of active defense, giving Knight more utility, (in addition to making the class just all around more defensive, for the most defensive class it took crazy damage) buffing his allies in some form. I liked Tyr's taunt as a knight skill, it meant the knight did what it had to, absorb the damage for the team, and it was balanced by the negatives that others hit him harder. It'd still protect the Summoner, but also all you allies. While it means your summoner still has problems when it comes to ambushes, those just seem like a legit way to defeat him. Naturally you can come up with your own ideas, or use that of others, I'm just pretending to help to get into the game!
EDIT: nvm spoilers if Agape already mentioned it. The most bulky summoner in the game, who was in SHADOW FORM, ended up being killed, the only true summoner death was the strongest summoner...
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