Once it lands, Tyrranax Rex has ward 4 and haste, meaning it is attacking as soon as it comes down, and even if your opponent wants to stop it, your opponents are going to be taxed to oblivion to resolve the spell
This isnt the only way you can build Muldrotha, however
Hasbro and Wizards of the Coast were roundly panned and accused of hatching a tone-deaf ploy to cash in on the nostalgia of fans with the deepest pockets or cater to the wealthiest collectors, who could go on to sell the cards at massive premiums
Activated ability allows you to draw a card for five mana and tapping it, but the cost is reduced by one mana for each rad counter you have
That's why Mill plays a lot of graveyard hate in the sideboard like Soul Guide Lantern or Extripate
However, during the first years of the game, there wasn't any support for it to be possible to build decks focused on them