Nalia de'Arnise

Nalia's last ability will check whether you have a full party at the beginning of combat on your turn. If you don't, the ability won't trigger. If the ability does trigger, it will check again as it tries to resolve. If you don't have a full party at that time, the ability won't resolve and none of its effects will happen.

You have a "full party" if the number of creatures in your party is four (that is, you control a Cleric, a Rogue, a Warrior, and a Wizard, and they are four different creatures).

If the top card of your library changes while you're casting a spell, playing a land, or activating an ability, you can't look at the new top card until you finish doing so. This means that if you cast a spell from the top of your library, you can't look at the next one until you're done paying for that spell.

The top card of your library isn't in your hand, so you can't take other actions that would normally be allowed from your hand, such as discarding it due to an effect or activating a cycling ability.