Just keep in mind that if you double attack triggers with Isshin or Wulfgar that only one trigger will resolve if they already sacrifice the permanent for the first trigger
Reward is multiplied by 5 if you win in less than 5 turns
This means that once you summon one and use its effect, you can immediately summon any other one and use its effect
But what really kicks it over the top is that middle part of his text box: Whenever an opponent casts a spell, if no mana was spent to cast it, counter that spell. You dont have to worry about an opponent casting a Force of Will while tapped out, or a free Fierce Guardianship or Deadly Rollick
In most of those older cards, the text might read something like: Whenever this creature would be destroyed, instead tap it, remove all damage from it, and remove it from combat. Thats basically the reminder text for how regeneration works