If I can successfully predict over half of an opponent's deck just by looking at their commander, it's not a casual deck.
It really doesn't matter what strategy they're playing.
This proposition doesn't actually work if the board is empty. If the board is empty, you'll have to put the -1/-1 counter on a scarab, and the loop becomes unstoppable and draws the game.
Edit: I'm wrong, this combo simply doesn't work.
Say you have a 1/1, and you put a counter on it. The nest trigger enters the stack, but then the creature dies as a state-based effect, then Blowfly goes on the stack. It resolves before you get a new token to put the counter on.
I'll quit a game so long as I don't think it will be any fun to play. If I find myself in a position where there's no way to come back, and I'm just going to be passing while everyone does stuff, I'll concede and find a new game. There's nothing wrong with admitting defeat, especially when playing on would be a huge time commitment. It's not like this guy table-flipped on you, he sounds perfectly respectful. You couldn't see his hand, it could have been mono seven-drops.
As for the mulls, that sounds a bit wierd, but I've left tables upon seeing more than one Nekusar before, so I can understand. He just wants to make sure he enjoys what time he's able to set aside to his hobby.
Play multiplayer?
Seriously, one-for-one decks only work in 2-player. And if you're struggling there, decks like Surrak or Geist or other threat-heavy decks that can justify Aether Vial can pick up wins.
If you're looking for sideboard pieces, Back to Basics can shut their lands off, Ensnaring Bridge can protect you if you have a burn wincon, Energy Field helps as a lot of their removal is exile-based.
Spirit is nice, depends on your format whether it's balanced. Much worse than Whitehawk.
In a limited environment, that crane is likely going to be draw 2 cards. Unless they have a bomb. Really bad punish for the stats, I don't think I'd play that, even with hexproof.
Rats has odd flavor. Why are rats searching for things? Raise dead effect is fine. But First Strike Deathtouch is something nothing should ever have in limited for any reason. This just wins the game against creature-heavy decks on turn 2.
Decisive Boar is way too good. 8 damage from hand with mediocre punishes in an aggressive deck. They need to be able to play the card for free. Even then, its the same as Crane/Rats in terms of search. I think it should be sac 2 lands or lava axe or something along those lines.
Bear is weak. The second mode is way too good. I think something like "may ramp or plow a land" would be better, or maybe "ramp or put 2 +1/+1 counters on a creature."
You can't really take "can't be countered" as important in limited as in constructed, unless your format is very counter-heavy, in which case it's very easy to make them too good. Be careful.
Unless you've explicitly passed priority, if he does that, the end the turn trigger goes on the stack on top of the dreadnought. I'm pretty sure a judge would rule he's countered his own spell.
It really doesn't matter what strategy they're playing.
Edit: I'm wrong, this combo simply doesn't work.
Say you have a 1/1, and you put a counter on it. The nest trigger enters the stack, but then the creature dies as a state-based effect, then Blowfly goes on the stack. It resolves before you get a new token to put the counter on.
Empty the Pits is much better.
As for the mulls, that sounds a bit wierd, but I've left tables upon seeing more than one Nekusar before, so I can understand. He just wants to make sure he enjoys what time he's able to set aside to his hobby.
Viscera Seer's sac outlet is an activated ability, and will be hit by the Harsh Mentor.
Seriously, one-for-one decks only work in 2-player. And if you're struggling there, decks like Surrak or Geist or other threat-heavy decks that can justify Aether Vial can pick up wins.
In a limited environment, that crane is likely going to be draw 2 cards. Unless they have a bomb. Really bad punish for the stats, I don't think I'd play that, even with hexproof.
Rats has odd flavor. Why are rats searching for things? Raise dead effect is fine. But First Strike Deathtouch is something nothing should ever have in limited for any reason. This just wins the game against creature-heavy decks on turn 2.
Decisive Boar is way too good. 8 damage from hand with mediocre punishes in an aggressive deck. They need to be able to play the card for free. Even then, its the same as Crane/Rats in terms of search. I think it should be sac 2 lands or lava axe or something along those lines.
Bear is weak. The second mode is way too good. I think something like "may ramp or plow a land" would be better, or maybe "ramp or put 2 +1/+1 counters on a creature."
You can't really take "can't be countered" as important in limited as in constructed, unless your format is very counter-heavy, in which case it's very easy to make them too good. Be careful.