You can shorten endure to "At the beginning of each end step, put X +1/+1 counters on ~, where X is the amount of (combat) damage dealt to it this turn." The main assumption being you can't put +1/+1 counters on dead creatures unless stated otherwise.
"Combat" is in parenthesis because I feel you can expand it to non-combat damage and it'll still be okay. Main underlying issue is that this can interact with indestructible and Blasphemous Act to get big in a jiffy.
Honor's just a worse version of Bushido. Chump blocks are still chump blocks if you don't give trample to synergize with it.
I understand Commanders having abilities that internally synergize, but I'm not certain about Commanders who are effective 1-card loops, even if said loop is dictated by your mana available.
Am I right to assume legislate is an alternate cost? Would this mean that, provided you can repeatedly pay the legislate cost, you get constant access to whatever you're exiling?
Rather than "Terras has Changeling...", I'd put "Terras gains all creature types..." instead. Check with various other Lorwyn spells that do that. Either way, it still feels underwhelming for a 4RGW 3/3. I believe you can tone down the mana cost to 2RGW or even 1RGW, seeing that you need a little extensive setup to get the boost.
Opai + Urborg = Commander rage. At least Opai has the cumbersome cost of 12 mana, but then again you can always cheat it in with Tooth and Nail or pals.