- More than one of the sexual aspects and at least a DW (double whammy), simple or combined.
Number one aspect: Venus/Mars in DW or in combination with another erotic aspect (combined DW). *for example, Venus/Mars, Mars/Moon
1. All Mars, in order, to: Venus, Moon, Pluto, Jupiter, Neptune, Saturn, Uranus, Sun, Mercury; from both sides, both Marses aspected like this.
2. Mars to an angle, especially ASC
3. Pluto aspects
More than two-three of these; the DWs/combinations should contain hard + soft, and soft aspects, at least a trine, a sextile, should be there, for longevity; especially the trine, the most longeval aspect; for example, a Venus/Mars, Venus/Pluto, Mars/Pluto trine does a great deal with this. But balance between hard and soft in the sexual part of the synastry is the most important thing: too much soft leads to boredom followed by separation, too much hard to intensity followed by separation.
4. 8th rulers in aspect or combinations with 8th/5th. 8th/5th overlays.
5. Also, 2nd house rulers or 2nd house overlays
6. Saturn and/or Pluto in some sort of connection to sexuality in synastry/composite
7. Only in addition to the planets, significant EROS (to personal planets and angles), and/or mutual aspects with personal planets/angels and erotic asteroids: Lilith, Lust, Amor, Aphrodite, etc.
Having many aspects on this list checked in the same synastry leads to long-lasting sexual spark and compatibility.