Can you dispel the effects of 'constant' spell-like abilities?
If so what type of action would it be to resume the effects? Free or standard? Or would they stay suppressed similar to a magic item?
Checking the rules (assuming we're talking about SLAs used by monsters).
"Spell-like abilities cannot be used to counterspell, nor can they be counterspelled."
So you can't directly counterspell an SLA as it it being used. That's not to say you can't counter the effects. If an SLA produces a fog-bank, a gust of wind will still push it away.
However, you CAN disrupt them. "A spell-like ability can be disrupted just as a spell can be." Ready an action and disrupt them as they're using it. Using them provokes, unless they do so defensively. "It is possible to make a concentration check to use a spell-like ability defensively and avoid provoking an attack of opportunity, just as when casting a spell."
"Reactivating a constant spell-like ability is a swift action. Using all other spell-like abilities is a standard action unless noted otherwise, and doing so provokes attacks of opportunity."
So if the SLA to be resumed is a constant SLA, then it's a Swift action to resume, otherwise it's a standard unless the SLA itself says differently.
A constant spell-like ability or one that can be used at will has no use limit; unless otherwise stated, a creature can only use a constant spell-like ability on itself. Reactivating a constant spell-like ability is a swift action. <-- Direct quote from the rules.
Yes, you can dispel even constant spell-like abilities just as you can normal spell-like abilities.
You can't counterspell them though, as SlimGauge noted. (That is, to stop it as it is being cast with dispel magic or an identical spell.)
Thank you both! I knew you couldn't counter spell them, I just wasn't sure of the action to reactivate them.
Can a creature dismisses its own constant spell-like ability if the spell it is emulating cannot be self-dismissed: like an Archon's Magic Circle vs Evil.
Sure you can re-activate them as swift action, but nothing is mentioned about deactivating them.
That would depend on the SLA. Some spells are dismissable and others are not. Any SLA based on a spell would follow that spell.