Basics:
Subterrors are a REALLY fun deck, and easy to play!
heres the basics:
1. you might wanna go second. going first usually hurts setting up.
2. your go-to is to get Guru, or Archer, on the field first. The goal is to bait archer into being destroyed, then special summon Umastryx, Speleogist, or Dragossuary. If its Guru, use the opportunity to activate its effect, flip the opponents monster facedown, and activate the ability to special summon the other behemoths.
3. Ash Blossom and Fiendess are practically the same, allowing you to cancel out quick effects. you only need 2 of each, you can try 3, but thats a bit overkill.
4. Ghost Belle is useful for getting your Guru and other monsters out of the graveyard. Use it wisely.
5. Ghost Belle and Ash Blossom also function as tuners for synchros, this will mean you can use them with Baronne and Rose Dragon.
a. Baronne is used to negate things like Maxx C, or Ash Blossom, as well as summong Level 9 or below monsters from your graveyard. Use this to Summon Umastryx, True King Lithosagym, or Dragossuary.
b. Rose Dragon is literally there as a nuke. when black hole wont work, rose dragon just might! summon her, and blast everything off the map. (LEGALIZE NUCLEAR BOMBS, SWAG MESSIAH!)
6. Most decks do not include Dragossuary, but with its effect combined with "Terrors in the Hidden City", it will make your subterrors immune to destruction whether they are face up, or face down.
7. Mirror Force and Wall of Disruption WILL save you more times than it wont. Theres likely a better meta method to defending your field, but i strongly endorse Mirror Force Propaganda.
8. Subterror Fiendess is a great signature monster, but alas, the meta will get you all eventually. alternatively, the other link monsters will assist in high level summons when your base deck isnt working. dont be afraid to do what you need to do to win.
9. Dracossack will need specifically, 2 Umastryx on the field. Dracossack will be useful in negating attacks when youre drawing for cards or setting up a summon.
10. Utopia and Dark XYZ Dragon are your Emergency high level monster summons. XYZ will eat one monsters attack away, and utopia will stall for 2 turns.
11. IF youre going to summon one of the big link monsters with 3000 attack, remember to use Masquerana to do so, this will make the monster impervious to CARD EFFECTS, which is incredibly useful.