Serperior, a quarter-box at smaller events, or a half-box if I'm the head judge. For larger events like States and such, it's a box for a full day, and if I come back on Sunday I get more, based on how many hours I work.
The effect of "Number 107: Galaxy-Eyes Tachyon Dragon" that negates the effects of all other face-up monsters and returns their ATK and DEF to their original values is applied as long as the affected monsters remain face-up on the field.
Tachyon Dragon negates the effects of monsters on the field. It will not negate effects that activate/resolve outside of the field. Thus, it does not negate Abysslinde's effect in the grave; however, if Abysslinde's effect is used, Tachyon Dragon will gain 1000 ATK and be able to attack again.
Serperior, in that case, go with what you have, and keep those Malefics alive. If you can, invest in Safe Zone.
Be careful of Pleiades, as they'll just bounce your Field Spell or Skill Drain. Black Horn of Heaven, Heraldry Record, Void Trap Hole, and Traptrix Trap Hole Nightmare will stop it - the last one stops a LOT of things.
Serperior, some variants of the deck use one that leans more towards Gravekeeper's (like Descendant, Spy, stuff like that) and has the Malefics as an aside.
Overall it looks solid, since you want to protect your Malefics once they get out. Though, if you wanted to go for another option for a Field Spell card, you could try Geartown if you wanted, since it gets you a free 3000 ATK beater (Gadjiltron Dragon) when destroyed. It looks good, but if I had to offer any other advice, I'd put in some more lv. 4s that can do stuff for you (Descendant is good for that since it pops cards).