If this card is Normal or Special Summoned: You can Special Summon 1 "Destiny HERO" monster from your hand with ATK less than or equal to this card's. You can only use this effect of "Destiny HERO - Drilldark" once per turn. If this card attacks a Defense Position monster, inflict piercing battle damage to your opponent.
Since it's attack can be pretty low in comparison to many commonly used level 4 monsters, you can increase its attack by using skills that give you the field spells, or bringing them in the deck. Joey's exclusive skill "Fields of the Warriors" gives you Sogen at the start of the duel, and Aster's skill "Destiny Calling" is for Dark City when your LP is at 3000 or lower.
Many of the level 4 or lower monsters have about 1600 or less attack, making them able to be special summoned if you also have these in your hand. They can be good in certain situations, but it's mostly good if paired up with The A. Forces to bump up your attack.
A good option to special summon using Drilldark's effect is to special summon Celestial. It has an effect that can destroy your opponent's face-up spell card when it declares an attack, but it also has an effect that lets you draw 2 cards when you have no cards in hand. This makes it so that even if it gets destroyed, it sets you up for your later turns, or get some of your resources back when you fusion summon Destiny HERO - Dangerous.
If you are hoping to bait your opponent into using a facedown, it can come across even better if you make it look like you are just trying to summon this guy to use his effect to swarm the field. My opponent used Gale Lizard's effect on my Trinity. Not long after, I summon Drilldark and start to use his effect. Sure enough, he Floodgates it. But what my opponent was not counting on was my second Polymerization waiting in my hand. Trinity is back and I win the duel. If I had had used Polymerization first, I would have lost my chance for the kill then.
I don't watch yugioh nor play it. So I don't understand why they don't standardize everything. Example: why Japanese name and English name? They could just use their original name in duel link.. You don't see toei rename son goku in DB FighterZ to Joseph Sun or something
There's plenty of reasons to localize things. Making them more memorable to other audiences, more relatable, certain things being untranslatable (like most of the Frog names for example), etc. Either way, it's the lack of consistency here that bothers me most. Most of the site uses TCG names. So all of it should be TCG names. You don't see Polymerization being called "Fusion" here, after all.