First, about the Rustler w/ adrenaline cost issue, adrenaline costs 4 (3 upgraded). It is true that this card would be a cheaper way of doing that. ("OP! OP!" shout the dissenters and detractors. "Hold up! ", I say, "Let me explain")
Adrenaline costs 4.
This costs 1.
However, Adrenaline may be used on a monster of your choice.
This one is used on a monster with only 1 attack, which wouldn't be a cost effective use of adrenaline normally.
"I am still not convinced!", cry the haters, though not as confidently as before.
"But wait! There's more!", I say smugly.
The coup de grace is that this only occurs part of the time.
Less than 100% chance to summon a 1 attack creature with adrenaline for the cost of
+ cost of the card, is not any more OP than spending 4
(3
upgraded) to apply adrenaline to a creature of your choice.
"Oh, ok." Say the detractors "We are convinced, and will name our first born after you"
"Ok, but you are probably not going to have children.", say I.
Oh, for the Gambler|Trickster, I though about it, and, instead of having the stats increase when the card is upgraded, the effect would slightly change (to make the names make sense)
For the Gambler, he would be taking a gamble, so he either gains a random Lucky Charm, or some negative effect happens to him (maybe delay or damage. Up to you).
For the Trickster, he is still leaving it up to chance, but both possibilities help him (stick with the original ability for this guy).
So, we would just need some art, find some fair stats, and a cost that the community would agree upon (mostly. They never totally agree, except for the large contingent against fractal...)