You can better protect your stuff by leaning into counters
So that means triggering your Hedron Crab also triggers this homarid mercenary, as would targeting them with something like Glimpse the Unthinkable
Also, the land comes in untapped if you have one land or less in play which makes it decent in the early game
Finally, it can protect itself by--you guessed it--discarding cards, meaning that you can also use it to throw down more huge creatures
With such rare cards as Hazezon Tamar, The Abyss, and, of course, Nicol Bolas and the other original legendary Elder Dragons, Legends is a scarcity in the present day
It will also teach you how to decide which planeswalkers to prioritize when you cant protect them all