Legendary creature spells you cast have convoke. (Your creatures can help cast those spells. Each creature you tap while casting a legendary creature spell pays for or one mana of that creature's color.)

Whenever your commander attacks, create a 1/1 red Mercenary creature token with ": Target creature you control gets +1/+0 until end of turn. Activate only as a sorcery."

When Woodland Bellower enters, you may search your library for a nonlegendary green creature card with mana value 3 or less, put it onto the battlefield, then shuffle.

, : Choose target enchantment you control that doesn't have the same name as another permanent you control. Create a token that's a copy of it, except it isn't legendary. If the token is an Aura, untap Yenna, Redtooth Regent, then scry 2. Activate only as a sorcery.

Whenever another legendary permanent you control enters, put a +1/+1 counter on Yoshimaru, Ever Faithful.

Partner (You can have two commanders if both have partner.)

At the beginning of your end step, if a land entered the battlefield under your control this turn and you control a prime number of lands, create Primo, the Indivisible, a legendary 0/0 green and blue Fractal creature token, then put that many +1/+1 counters on it. (2, 3, 5, 7, 11, 13, 17, 19, 23, 29, and 31 are prime numbers.)