For reference, the relevant text of "Uh, Yeah, I'm That Guy":
treat this card as if it had the game text of every ongoing card in that player's play area, replacing their hero's name with Guise.
This requires some interpretation when applied to The Sentinels.
- Should you interpret it to say "replacing their heroes' names with Guise"? I should think so; this is usually the way you "translate" things to work with The Sentinels. So you'd replace the names of any of the four heroes where they appear on one of their ongoings.
- Sentinel Tactics reads, "The first time one of The Sentinels deals damage each turn, you may use a power." Is "The Sentinels" considered to be the name of a hero? Is their setup card considered to be a hero character card? If so, this becomes "The first time one of Guise deals damage each turn, you may use a power," which is gramatically strange but can be followed in a logical way. If not, it can still be followed in a logical way (when a Sentinel deals damage, Guise can use a power). But I'm not sure which is correct.