Yeah i totally agree with you. I'm pretty fair when it comes to play-testing against myself as i want my deck to work, and finding its weaknesses is the best way to do it, but its of course impossible to do it 100% accurately. 5/60 is still better than 4/60, and i haven't had problems with 4/60 yet, so the additional chance is put in purely on your result. Its still a better chance than any play-set, so i think it should be fine.

For offcolors, i have 1 Negate in there now, and im thinking of Journey to Eternity as a means to protect and bring Ruthless Knave back from the graveyard. The other option is Cut / Ribbons as an alternate win-con, but i dont have room yet. I need anti-enchantment stuff for Ixalan's Binding mirrors, and i need Duress as its the best Disallow bait.

I've now been testing against Rivals of Ixalan Merfolk by Corbin Hosler

The board wipes help, but that deck can re-establish itself very quickly.

All the +1/+1 Counters help it to get its most important Merfolk our of the range of Yahenni's Expertise.

Spell Pierce is a problem for this deck.

You either have to play around it, meaning playing Torment of Hailfire for two less, or take the chance that they don't have it, tap out, and then not be able to stop the counter spell.

Oh yeah totally agree. The first Torment of Hailfire probably needs to be case a little conservative, but with the help of treasures it is possible to play a strong spell while keeping 2, or even 3 manna up. Standard has lots of counter-spells that can be played around with enough manna(which is what this deck is all about). Censor, Spell Pierce, Supreme Will and Lookout's Dispersal are all potential dead cards once the treasure count is up. The only counter spells that threaten us once we have some treasures out is Disallow, Negate, Essence Scatter and Cancel/Admiral's Order. In Tempo builds 3 manna counter-spells arent common, and control builds like Supreme Will and Censor a lot, and they generally dont really favor Cancel/Admiral's Order. Essence Scatter doesnt stop our win-con, so that leaves Disallow and Negate as our most serious threats against control, and possibly Admiral's Order in tempo builds. The Duress in the side-board is meant to bait these out. It only costs 1, and if they use any other counter-spell, we can dodge it with our manna. This forces one of these large threats out of their hand. If they dont use them, we take them. Against those 3 spells i would bring in Duress. I think Spell Pierce can be played around, but we can always bring in a Negate of our own to deal with it. Im thinking of putting a 2 of Negate in the sideboard, as i think its playable in the mainboard for the purposes we will use it, to defend Torment of Hailfire.

Did some more play-testing. You have to find Start / Finish to deal with major threats, as it saves so much time. You chump, next turn you kill and you still have 1 chump blocker left. Added another copy of it. The other thing i saw was that the difference between a 1/1 and a 2/1 is colossal within the first 3 turns of play. by turn 3 Sacred Cat is relegated to a chump blocker with no means to actually trade. It also forces me to spend another manna on the next turn for the token, which is the same creature as the one Martyr of Dusk creates upon death. It seems faster, but if you dont drop Sacred Cat turn 1, it actually isn't, in fact it is sometimes slightly slower. I think as the deck is now it has an optimal early game.Another huge theme that keeps popping up against aggressive decks is the fact that if i dont draw Oketra's Last Mercy, i better hope my opponent has a sub-optimal draw because it saves this deck from a loss time and time again. I play-tested this against that merfolk deck and got properly stomped because i didnt draw into Oketra's Last Mercy and i missed 2 land drops. That is its other problem. I am running 11 4 manna spells, and granted, thats where the curve ends but still, there are so many of them if you miss a land-drop its worse than it is for any other deck i've ever run. Almost makes me wanna go to 24 lands, but i wouldn't know what to replace. I mean the odds that i miss a land drop while not finding any treasures to compensate is pretty small, but still. As to how i playtest against myself, my golden rule is to restart until the other deck has a good starting hand, while with the one i am testing i play with mulligans as i would in a real match. This gives a makeshift handy-cap to the deck i am testing against to make up for some bias.