Certainly! To create a test case generator for the Goldbach's Conjecture problem, we need to generate even numbers between 4 and 214. Here's a Python function that generates such test cases:

```python
import random

def generate_even_number():
    """Generates a random even number between 4 and 214 inclusive."""
    return random.choice(range(4, 215, 2))

def tcgen():
    """Generates a sequence of test cases for the Goldbach's Conjecture problem."""
    
    # Random number of test cases between 1 and 20 (arbitrary choice for variety)
    num_cases = random.randint(1, 20)
    
    # Generate the test cases
    test_cases = [generate_even_number() for _ in range(num_cases)]
    
    # Add the terminating zero
    test_cases.append(0)
    
    return test_cases

# Example usage
test_cases = tcgen()
for tc in test_cases:
    print(tc)
```

### Explanation:

1. **`generate_even_number` Function**:
    - Generates a random even number between 4 and 214 inclusive.
    - Uses `random.choice` on the range of even numbers starting from 4 to 214 with a step of 2.

2. **`tcgen` Function**:
    - Generates a random number of test cases (between 1 and 20, for example) to ensure variety.
    - Uses a list comprehension to generate the specified number of even test cases using the `generate_even_number` function.
    - Appends the terminating zero to the list of test cases.
    - Returns the list of test cases.

This generator will produce a varied set of even numbers as required by the problem, while ensuring the termination with 0 as specified.