Cleon
Legend
Those look good. I was a bit confused on the epic feats (why not Epic Skill Focus (Hide), for example), but I see the ranks don't let it qualify. Do you think DMs might find that confusing?
Perhaps the following clarification?
Feats: A Mystaran gargantua retains the feats of the base creature and gains additional feats according to its increased hit dice. If it gains epic feats, it can substitute epic equivalents of the base creature's feats instead of retaining the base creature's feats, assuming it meets the prerequisites. For example, the Mystaran gargantua constrictor snake below may replace its Toughness feat with Epic Toughness, but cannot replace Alertness with Epic Skill Focus (Listen) and Epic Skill Focus (Spot), because it lacks the 20 rank prerequisite in those skills.
In addition, it gains Snatch as a bonus feat. If the Mystaran gargantua has a fly speed it also gains Hover as a bonus feat.
Yes, that 'tis an improvement.
I'd use "provided it meets" instead of "assuming it meets".
It's debatable whether the example is necessary, but I think it's better with it.