Does Torpor Orb stop triggered abilities that trigger on attacking or only on entering the battlefield?

Torpor Orb reads: 'Creatures entering the battlefield don't cause abilities to trigger.' Its effect is precisely limited to triggered abilities that trigger off a creature entering the battlefield (i.e., 'enters the battlefield' or ETB triggers). It has absolutely no effect on triggered abilities that trigger when a creature attacks, becomes tapped, or meets any other condition.

This is a textual-scope question governed by CR 603.1, which states that triggered abilities use 'when,' 'whenever,' or 'at' and trigger based on the specific event named in their trigger condition. Torpor Orb modifies only one specific category of trigger event: a creature entering the battlefield (CR 603.6 covers how replacement and prevention effects interact with triggers, and Torpor Orb functions as a blanket prevention of that one trigger category).

So if a creature has both an ETB trigger ('When ~ enters the battlefield, do X') and an attack trigger ('Whenever ~ attacks, do Y'), Torpor Orb suppresses only the ETB trigger. The attack trigger fires as normal whenever that creature is declared an attacker per CR 508.1.

Example: You control Torpor Orb and your opponent plays Thragtusk. The 'When Thragtusk enters the battlefield, you gain 5 life' trigger is suppressed by Torpor Orb. However, if Thragtusk then attacks, any triggered ability that says 'Whenever Thragtusk attacks…' would still trigger normally, because Torpor Orb does not care about attack triggers.

In summary, Torpor Orb is narrowly scoped. It is not a general 'no creature triggers' effect — only ETB triggers from creatures are shut off. Always read the card carefully to confirm which trigger event it names (CR 109.1: cards say exactly what they do).