Some time ago I allowed a small earth elemental as an improved familiar for a pc wizard.
It took about two sessions before I had to take it away and give him another familiar. The earth glide ability wreaks havok with most adventures in the hands of a clever player. It would only get worse if it was the player rather than a familiar who had that ability.
The scouting potential, bypassing/disrupting traps and barriers potential, stealth potential, casting/attacking with only hands and head above ground potential etc. is very hard to deal with in my experience.
It took about two sessions before I had to take it away and give him another familiar. The earth glide ability wreaks havok with most adventures in the hands of a clever player. It would only get worse if it was the player rather than a familiar who had that ability.
The scouting potential, bypassing/disrupting traps and barriers potential, stealth potential, casting/attacking with only hands and head above ground potential etc. is very hard to deal with in my experience.