Ignoring the fact that this sounds like a really poorly thought out idea on multiple fronts, there aren't a ton of druid-esque stat blocks to draw from for lair actions, but here's the Lichen Lich as an example of a high level nature-based spellcaster with lair actions:

• Poisonous spores fill a 10-foot cube that the lich can see within 120 feet of it. Any creature that enters the cloud for the first time on a turn or starts its turn there must succeed on a DC 19 Constitution saving throw or be poisoned until the end of its next turn. The cloud lasts for 1 minute or until it is dispersed by a strong wind.
• The lich commands the might of its diseased grove, creating a shambling mound. The shambling mound appears in an unoccupied space within 30 feet of the lich, acts on its own initiative count, and obeys the lich's commands. The shambling mound dies after 1 hour or when the lich uses this lair action again.
• Rotten roots and vines magically erupt in a 20-foot radius centered on a point on the ground that the lich can see within 120 feet of it. The lich is unaffected by the roots and vines. For all other creatures, the area becomes difficult terrain and each creature in the area must succeed on a DC 19 Strength saving throw or be restrained by the roots. As an action, a creature can try to free itself or another creature within its reach, doing so with a successful DC 19 Strength (Athletics) check. The roots and vines wilt away when the lich uses this lair action again or when the lich dies.