DTBS Explanations

DTBS: Defeat Twinrova with the Biggoron Sword
Rule Infographic:
http://imgur.com/a/biMI5

Detailed rules and route implications:

Banned Items (cannot be obtained by source, rba or ba)

Fire Arrows - prevents RBA of the Fire Temple Boss Key, requiring quickspin room + flare dancer

Hookshot - Prevents entering Forest Temple early and slowing down BA for Eyedrops/Farore's Wind/Megaton Hammer

Deku Nuts - Prevents using Fish for BA, thus reliance on Poes is necessary

Eyeball Frog - Forces Eyedrops to be acquired through Bottle Adventure only

Fairy Bow - Forces the need for Din's Fire in Water Temple, and enforces longshot requirement for Phantom Ganon

Bugs - Limits RBA options, not particularly serious

Goron Mask - ??? Presumably limits RBA ???

Bomb Bags 20/30/40 - Limits use of bombs at one at a time with full milk rba, requiring strategic planning with bombs

Hylian Shield - Limits everything. Biggest restriction of the route. No Hylian Shield means no PCS, limiting combat to jumpslashes/quickspins for speed. Limits methods of getting bottle on B as adult link to the fishing pond at lake hylia.
Furthermore, no hylian shield means no ISG, superslides, HESSes or bomb hovers as adult link.

Goron Tunic - limits RBA, and makes fire temple more difficult

Zora Tunic - Not really necessary, could be useful in water temple with iron boots?

Requiem of Spirit - Makes the wrong warp to spirit temple one way, need to be prepared for spirit on arrival

Additional Restrictions:

Using bombchus inside temples is banned - Limits explosive use in temples to one bomb which must be replenished with Milk RBA

NEVER enter child dungeons as adult - Prevents wrong warps with Deku and Dodongo's Cavern

Banned from Entering/Crossing Haunted Wasteland - Forces wrong warp with fire temple to spirit temple

Version specific tricks banned - Not really a huge effect other than no stick on B for VC

3 Hearts Only - More of a challenge, makes fire temple difficult

No Half-Milk RBA - Doesn't really effect much. Isn't particularly useful.