With Undertitian does playing it proc the on reveal?

No, playing Undertitan does not trigger its "reveal" ability.

According to the official FAQ regarding Undertitan:

• Drawing is not revealing: Drawing a card is a distinct game action from revealing one.
• Reveal is a specific limited action: The ability "As I'm revealed from your deck" only triggers when a game effect explicitly instructs you to "Reveal" cards from your deck. Simply playing the card from your hand or another zone does not count as revealing it.

As stated in Rule 411.2.a, players may only reveal cards from private or secret zones when instructed to do so by game effects. Because playing a card is a different process (Rule 406), it does not satisfy the condition for the reveal-based ability.