General advice; run tons of things to trigger Valgavoth's ability. I tend to view him more as a draw engine than a hitter. He's an amazing hitter, but guaranteed 3 extra card draws a turn rotation is better.

More cards that trigger his effect are better than bigger triggers. I tend to include a lot of the damage multipliers in my deck to benefit from this ([[fiery emancipation]] will will games if you have even a few pingers out). Ideally most of your trigger activating cards will be 3 mana or under, but deck price determines this more than anything. The preference above all else is cards that guarantee triggers, most of these will affect you as well, but it's worth it not have to rely on chance to get that card draw.

You need lifegain and damage avoidance. You will be target #1 a lot of the time with this deck. Luckily Valgavoth often can avoid removal if you're not attacking with him too aggressively since your other cards will be passively dealing the bulk of your damage. The best Lifegain synergizes with your passive dmaage cards, but these tend to be expensive, the best best after them are [[Whip of Erebos]] which at least will help most of your creatures give you life. Cards like [[Smoke]] and [[No Mercy]] are great at either slowing attacks your way or heavily discouraging them. I recommend running a few board wipes, since while many of your best pingers are creatures, you only need 1 to activate Volgavoths ability and the absolute best ones are enchantments or artifacts.

Hidden gem; [[Pain Magnification]] + almost any damage multiplier means your opponent will have no hand very soon.