"Grand Strategist" isn't a standard Magic keyword or ability—it doesn't appear in the comprehensive rules or on any official card as a defined mechanic. If you've seen it, it's likely flavor text, a creature type/title on a specific card, or a homebrew/custom card term rather than an actual rules keyword.
If you encountered it on a real card, the relevant rules come from that card's actual printed abilities, not from the name itself. Magic names never carry inherent rules meaning—only the text in the abilities box matters. So check the oracle text for what it genuinely does.
If you meant a different keyword (like Strategist as a token-maker, or a planeswalker ability), let me know the exact card or spelling, and I'll break down its rules, common misplays, and Commander relevance accurately.