Yes, a player can excavate or entice multiple times in a single turn if a card ability explicitly allows it. The rulebook states that "Although you may add multiple cave cards to your player mat each round, every time you take the excavate action, you may only excavate 1 space (unless the cave card you play directs otherwise)" (Page 5). This indicates that card abilities can override the standard limitation of excavating or enticing only once per turn.

Summary

• By default, players can excavate or entice only once per turn.
• If a card ability explicitly allows additional excavations or enticements, players may perform those actions multiple times in a single turn.

This conclusion is based on the rulebook's clarification about card abilities potentially modifying the standard rules.

Source: Wyrmspan Rulebook (pp. 1, 10, 11, 5)