300 in a week means 43 a day... Just getting a dozen isn't even close.
You forget that guards keep leveling up, and getting harder.
To kill 300 of those by yourself, you'd need to do a collective 45550 million dmg. That's aroung 6507 full attacks. Even factoring natural focus regen, and using potes on every guard, that's still almost 2920 full attacks at max posible whale SED (around 950mil times 7 from all slayers maxed).
The point of these ultra guards has always been about sharing them between players, as having 50 or so friends fighting them alongside yourself means reaching the 300 hit mark without fighting anything above Lvl150 (reducing the total dmg needed to 22650, less than half the original amount), plus dividing the dmg between 10 to 20 players.
With those numbers, a team of whales with 7 slayer cards only needs less than 230 full hits each to reach 300 take downs.
That's theoretically doable in a week with only natural focus regen and no puddings involved.
In reality, it's not doable without puddings just because of the time limit imposed on the guard.
In the end, the only way anyone is going to get that limmed SR is by throwing a lot of money into PPS, or by two dozen whales somehow organizing themselves to hit each other's ultra guards.
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Don't even try to reach those 300 as a F2P player.
Max dmg by a F2Per is currently sitting a bit shy of 1mil SED after counting the N-Slayer.
That means that a team of 20 F2Pers would need around 1600 full attacks to take down those 300 ultra-guards. That's 210 full attacks per day.
Please, remember that you can't buy more than 140 puddings per day (10kpts/10u daily limit: 2x50 puddings offer + 2x20 puddings offer).
That, plus your 48 daily regens, doesn't reach those needed 210 attacks.
This means you're either throwing a lot of money on both e-gacha+reveal and a moderate ammount of puddings, or you're throwing a lot of money on a small set of e-gacha+reveal and a big ammount of puddings.
Anyway, those 300 guards are unobtainable by F2Per.
I don't mind that much, those are prizes for people willing to throw money to Nutaku, and that's okay with me.
But the numbers for this phase just make half the event completely useless for 90% of the player base.
I would have liked to at least reach the 100 ultra-guards milestone.