Lifegain Triggers: When it's once and when it's all
Before anyone asks, I have a reason for using a smaller picture of Ajani's Pridemate (magiccards.info currently doesn't have the newest set uploaded). On the older Ajani's Pridemate, it had clarification text, but this one doesn't (I don't know why), but here's where the confusion sets in: if a card says "whenever you gain life, do X", it means do X once. Unless is specifies otherwise, like with Ageless Entity, each time you gain life, regardless of how much you gain, the trigger happens once. Gain 1 life from Angel's Feather? That's one counter on this. Gain 8 life from Elixir of Vitality? This still only gets one counter. If you were to have 2 Angel's Feathers however, this will trigger once for each Feather trigger of lifegain since it's from two separate sources. In short, no matter how much life you gain, things like this will only trigger once per source, not per point.
Morph: The stackless ability
When people talk about split second, they talk about it like there's no way around it: those spells are infallible. Those people, however, don't know Magic rules as well as they think they do. Rule 702.35d states:
"If you have priority, you may turn a face-down permanent you control face up. This is a special action; it doesn't use the stack (see rule 115)"
Since split second specifies that player's can't activate abilities or play spells on the stack, you'd think that would cover morph, right? Well, since it's a "special ability", morph ignores that and is allowed to be performed once the split second spell's caster passes priority (which they have to do even if they think no one can respond to it). Turning a creature face up triggers their ability, meaning that split second doesn't stop that either (it only stops activated abilities). So, next time someone tries to Extirpate your wincon, flip over your Willbender and take theirs out of the game instead.
Copiable Text: What is it?
When a creature is copied, the copy basically has all of the text that's on the original card. It's really that simple. If you copy a land that's been animated for a turn, you get a copy of the land, not the creature. This can definitely lead to some shenangians. My favourite way to abuse this is the following: wait for someone to declare attacks at you (or someone else), wait for everyone to have exhausted their combat tricks, then use Animate Land and Mirrorweave to turn everything into a land until the end of turn.
I think that's enough learning for today. I hope to do more of these soon, and if you have anything you'd like clarified, please feel free to let me know!