Slimefoot and Squee

Whenever Slimefoot and Squee enters or attacks, create a 1/1 green Saproling creature token.
{1}{B}{R}{G}, Sacrifice a Saproling: Return this card and up to one other target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Hellkite Overlord

Flying, trample, haste
{R}: This creature gets +1/+0 until end of turn.
{B}{G}: Regenerate this creature.

Dragon's Herald

{2}{R}, {T}, Sacrifice a black creature, a red creature, and a green creature: Search your library for a card named Hellkite Overlord, put it onto the battlefield, then shuffle.