Since Glenn only has one power and skulk, it can only be blocked by creatures with one or less power, which often allows you to cards when you connect to an opponent
Ferocious Bellow: 80 During your opponent's next turn, attacks used by the Defending Pokmon do 50 less damage (before applying Weakness and Resistance)
For Master Duel format, I would advise something around 0.62 - 0.70, the reason being that Master Duel decks have the "N/R/SR/UR" tags on the cards, which throws off object detection to some significant extent, so you'll need to compensating by reducing the accuracy coefficient threshold
You can also get more benefits along the way, which offsets the fact that your creature will be gone in a few turns
The card is basically all-powerful, and Yugi was only able to beat it through wild logic leaps, which included his monsters bouncing their attacks off of one another in order to power each other up
"Red-Eyes Insight" fills the GY and fetches cards like "Red-Eyes Fusion" with which "Meteor Black Comet Dragon" can be summoned, further setting up the GY while dealing burn damage and even bringing back Fusion Material if it is destroyed