Toolcraft Exemplar
Creature — Dwarf Artificer
At the beginning of combat on your turn, if you control an artifact, this creature gets +2/+1 until end of turn. If you control three or more artifacts, it also gains first strike until end of turn.
"If you wish to produce the finest work, you must start with the finest tools."
Zezhou Chen
Kaladesh (KLD)
• #32Rulings
Whether or not you control three or more artifacts is checked only as the triggered ability resolves.
(wotc • 2016-09-20)
If you control no artifacts as your combat phase begins, Toolcraft Exemplar's triggered ability doesn't trigger at all. If you control no artifacts as the triggered ability resolves, it has no effect.
(wotc • 2016-09-20)
Rulings
Whether or not you control three or more artifacts is checked only as the triggered ability resolves.
(wotc • 2016-09-20)
If you control no artifacts as your combat phase begins, Toolcraft Exemplar's triggered ability doesn't trigger at all. If you control no artifacts as the triggered ability resolves, it has no effect.
(wotc • 2016-09-20)