Bel'Veth

Nowhere is Safe

Lane harassment and consistent damage output.

Improved attacks and sustained damage

Conqueror

Gain stacks of adaptive force when attacking enemy champions. After reaching 12 stacks, heal for a portion of damage you deal to champions.
Triumph

Takedowns restore 5% of your missing health and grant an additional 20 gold.
Legend: Alacrity

Takedowns on enemies grant permanent Attack Speed.
Last Stand

Deal more damage to champions while you are low on health.

Creative tools and rule bending

Magical Footwear

You get free boots at 12 min but you cannot buy boots before then. Each takedown you get makes your boots come 45s sooner.
Cosmic Insight

+18 Summoner Spell Haste
+10 Item Haste

Conqueror is a solid rune choice for Bel'Veth because her fighting style is all about ramping damage with very fast auto attacks.

Bel'Veth benefits from Triumphs takeheal heal massively paired with her ultimate resets in extended fights.

The majority of Bel'Veth's damage is from auto attacks, so Alacrity is a great choice to make sure you can land as many of them as possible.

Last Stand is a great choice for extended fights where you are trying to eek out as much damage as possible.

Magical Footwear is stable economic rune choice allowing you to hit your 2 item spike as quickly as possible.

Cosmic Inisight is a generally good fallback rune when no other option is particularly great.