Tabernacle is a no go for Urza. This deck can't afford to sac or force tap its construct in a competitive setting plus this card is anti ramp. Opponents gain a huge lead against Urza decks 100% of the time this card is played unless each opponent has out at least 4 creatures when it's played (in which case they are already so far ahead of Urza that there's usually nothing that can change that). Can't use Tabernacle in a deck that relies on getting its commander out early and often when that commander is a 2 for 1 in terms of body count.

jaymc1130, thanks for the heads-up!

I thought running Tabernacle would be a good fit considering the low creature count in this deck, as a way to control decks that rely on creatures, but what you say makes sense!

@ Byuante I fell into the same trap to be honest. Took a half dozen losing games where I played it to realize it was counterproductive for competitive play.