Clipping is cancelling animations (weapons or power animations) with other powers/sodas/trinkets/etc. For example, tap 4x's hold with martial arts has a slow animation - you can animation cancel the last hit of the combo by casting a power. The net result is a faster style of gameplay and greater burst damage.
is it necessary? most say yes, as it allows you to get more damage/healing/power out and is generally pretty easy once you learn how and what cancels.
From the limited amount of clipping I know (and I could be wrong): This is the usual order of clipping: Weapon Combo -> Offensive Power (Enflame) -> Buff Power (Fiery Weapon) -> Trinket / Consumable (Eerie Jack / Soder) Or sometimes I tend to do a BlockBreaker and clip Fireball. There are some long-cast powers that can't be clipped or it won't work: Mass Detonation, Fire Burst, Flame Cascade. There are some powers that can be Jump-Canceled (hitting jump as soon as you use the power): Detonation -> Jump-Cancel I never used Light Powers, but very good players use a lot of clipping and jump-canceling with it. Some players using Brawling tend to hide their Block Breakers by hitting BB right after a power. You'll see this a lot with Lantern characters in Legends. Lots of players like 1handed because of the Spin Chop (tap tap hold) -> Power. Easy to do for a 3-move combo that does good damage compared to other moves. Also I've seen people use 2Handed Doom Spin into a BB, something useful if you're using Harley in Legends.
I only Clip in Legends PvP. It's not really that necessary solo. That and I like to see my actual weapon animations. I also don't recommend Clip spamming in Alerts when you have no controller unless you're prepared to spend a lot of time getting your own power back. The reason being is that in order to Clip you have to use a Power, as stated above, so simply attacking only two or three times between each Power use will eat up a lot of your power. I've done this as Light just to see what it's like (Ram->Snap Trap->Fan~Jump Cancel->Ranged Tap~Ram Clip~Repeat endlessly). Once the power is gone, with no controller it takes a while to get back, even by spamming Doom Spin. In short, I feel Clipping is situational, main for when you need to do a lot of damage fast or when you have an "unlimited" power pool. If it's not one of those two, it's probably more efficient to go with using Power Interactions and your 50% damage buff followed by weapon combos to Tier 3 power regen (i.e. the numbers on your hit counter are orange). This will probably do better damage in the long run than blowing all your power all at once. Unless that doesn't bother you, in which case go and do it. Most DPS do anyway. I just hate seeing my own power bar drop below 50% (I like knowing I can use a Breakout if i need it).
I think there are some moves that can't be clipped without losing the effect of the move you're trying to clip. For example, on my Sorcery Healer, Cast Soul Well has a long animation which also prevents me from moving and/or blocking while the animation is in progress. So I cast Rejuvenate right after casting Soul Well, and get the healing out from both moves without having to wait out the animation. This is good. But I've tried clipping Invocation of Renewal with Rejuvenate (Invocation has a very long animation), and I don't think the heals from Invocation go out if I clip it before the animation finishes. If I'm wrong about this, I'd appreciate knowing. As it stands, I avoid clipping Invocation of Renewal except in emergencies.
I do notice that you can't clip Lunges. At least they don't work for me. The character leaps forward but no damage is done. Same goes if I use Hammer Throw.
